Your post definitely fueled my inspiration to try an alternative (especially for Cloud). It's fairly code intensive, but it retains Signatures using only a single HTML Field, a signature field for each user, and a hidden single line field for each user (no workflows and only a single form).

  A note that this process is completely internal and none of those users even know how to get to the developer console (not sure if the following practices are best for security).

 1) First, we assign many user tasks the same single form through a Parallel Gateway.

2) Second, we design a form with an HTML field to get the current user with the following code:

 a) Inside the HTML <> itself: {/_currentuser}

// b) Then, for the JS on the Form (cloud):
const htmlField = xxx // Hidden HTML Field Id - your integer number here!!
const currentUser = LFForm.findFields(f => f.fieldId === htmlField)[0].settings.default // HTML field that holds Current User (String)
LFForm.hideFields({fieldId: htmlField})

// 3) Third, we'll also name all the fields we use on the form (just an easy way to not keep reusing fieldId's)
// Department Signature COLLECTION
// User1
const _user1Sign = {fieldId: xxx} // Required Signature FieldId Number
const _user1SignText = {fieldId: xxx} // Single Line Signature Link Saver
// User2
const _user2Sign = {fieldId: xxx} // Required Signature FieldId Number
const _user2SignText = {fieldId: xxx} // Single Line Signature Link Saver
// User 3
const _user3Sign = {fieldId: xxx} // Required Signature FieldId Number
const _user3SignText = {fieldId: xxx} // Single Line Signature Link Saver

// a) Then, let's hide all the text fields:
LFForm.hideFields(_user1SignText, _user2SignText, _user3SignText)

// 4) Fourth, in the Cloud JS, we need to call a function we'll use:
forSignatures()

// a) Then, we'll actually write our forSignatures() function:
function forSignatures () { console.log("===FUNCTION: forSignatures() CALLED: ", currentUser)

    let [ user1SignText, user2SignText, user3SignText ] = [ LFForm.getFieldValues(_user1SignText),
        LFForm.getFieldValues(_user2SignText), LFForm.getFieldValues(_user3SignText) ]

    // Testing
    console.log (user1SignText, user2SignText, user3SignText);

    // Program using switch statement
    switch (currentUser) {
        case "<User1 Username> ": // Change the form if User 1 is viewing:
            LFForm.changeFormSettings({title: "User 1's Form Title", description: "Form for User 1."}); // Rename Form
            LFForm.hideFields(_user3Sign, _user2Sign) // This can be altered IF full later...
            LFForm.enableFields(_user1Sign) // So the current user can sign their current field

            // Optional You may want to add Highlighted CSS classes to where the User should sign.
            LFForm.addCSSClasses(_user1Sign, "yellowHL");
            LFForm.removeCSSClasses([_user3Sign, _user2Sign], "yellowHL"); 

            // Make sure the User's Signature is always captured for the Saved Single Line (Hidden)
            LFForm.onFieldChange(()=> updateSignature(_user1Sign, _user1SignText), _user1Sign)

            // If the current user overwrites the wrong fields...
            if (user3SignText) {
                LFForm.onFieldChange(()=> updateSignature(_user3SignText, _user3Sign), _user3Sign)
                updateSignature(_user3SignText, _user3Sign)
                LFForm.showFields(_user3Sign)
            }
            if (user2SignText) {
                LFForm.onFieldChange(()=> updateSignature(_user2SignText, _user2Sign), _user2Sign)
                updateSignature(_user2SignText, _user2Sign)
                LFForm.showFields(_user2Sign)
            }
            break;

        case "<User2 Username> ": // Similar to User 1 except adjusted values for User 2.
            LFForm.changeFormSettings({title: "User 2's Form Title", description: "Form for User 2."}); // Rename Form
            LFForm.hideFields(_user1Sign, _user3Sign)
            LFForm.enableFields(_user2Sign)
            LFForm.addCSSClasses(_user2Sign, "yellowHL");
            LFForm.removeCSSClasses([_user3Sign, _user1Sign], "yellowHL"); 
            LFForm.onFieldChange(()=> updateSignature(_user2Sign, _user2SignText), _user2Sign)
            // If the current user overwrites the wrong fields...
            if (user3SignText) {
                LFForm.onFieldChange(()=> updateSignature(_user3SignText, _user3Sign), _user3Sign)
                updateSignature(_user3SignText, _user3Sign)
                LFForm.showFields(_user3Sign)
            }
            if (user1SignText) { LFForm.onFieldChange(()=> updateSignature(_user1SignText, _user1Sign), _user1Sign)
                updateSignature(_user1SignText, _user1Sign)
                LFForm.showFields(_user1Sign)
            }            
            break;

        case "<User3 Username> ": // Similar to User 1 except adjusted values for User 3.
                LFForm.changeFormSettings({title: "User 2's Form Title", description: "Form for User 2."});
                LFForm.hideFields(_user2Sign, _user1Sign)
                LFForm.enableFields(_user3Sign)
                LFForm.addCSSClasses(_user3Sign, "yellowHL");
                LFForm.removeCSSClasses([_user2Sign, _user1Sign], "yellowHL"); 
                LFForm.onFieldChange(()=> updateSignature(_user3Sign, _user3SignText), _user3Sign)
                // If the current user overwrites the wrong fields...
                if (user2SignText) {
                    LFForm.onFieldChange(()=> updateSignature(_user2SignText, _user2Sign), _user2Sign)
                    updateSignature(_user2SignText, _user2Sign)
                    LFForm.showFields(_user2Sign)
                }
                if (user1SignText) { LFForm.onFieldChange(()=> updateSignature(_user1SignText, _user1Sign), _user1Sign)
                    updateSignature(_user1SignText, _user1Sign)
                    LFForm.showFields(_user1Sign)
                }     
                break;
        default: // In case something breaks...
            LFForm.changeFormSettings({title: "ERROR: Username Unrecognized", 
                description: "Please Contact your Records Analyst to resolve this issue."});
            LFForm.disableFields(_user3Sign, _user2Sign, _user1Sign)
            LFForm.removeCSSClasses([_user3Sign, _user1Sign, _user2Sign], "yellowHL"); 
            break;
    } 
}

// 5) Lastly, you may notice a function used that we'll have to define called updateSignature()
function updateSignature (_signField, _signSave) { console.log("===FUNCTION CALLED: updateSignature()", _signField, _signSave)

    let newSignature = LFForm.getFieldValues(_signField)
    let saveSignature = LFForm.getFieldValues(_signSave)
    if (newSignature.length > 0) { if (saveSignature !== newSignature) LFForm.setFieldValues(_signSave, newSignature); }
}

In my testing, no additional workflow is needed to save / display signatures as they are input (not to mention I could NOT get a workflow to do what I wanted, as the signature variables weren't selectable in my business process?? I also didn't want to do some fetching from field values on saved forms or something weird ). Also, the updateSignatures() function imputes the signature field and FORCES an update to the default value if the wrong user tries to overwrite it. 

I also had an onSubmission function... but I'm thinking it's deprecated with this method when the signatures are required fields. 

 I'm sure there's optimizations available depending on how many users you have, I just had 3 though and found the idea of multiple forms / workflows exhausting.