If you're just using them in Assign Field Values, then it's not necessary, the Laserfiche Server will enforce the new type. Workflow also does attempt to fit things into formats even when their data type doesn't match, so you probably don't have to review value formatting (for ex, if you have a text field with YYYY-MM-DD date formatting, that's expected to give you a valid date if you start out with "10/15/2025" because the value is a proper date even though the field is a text field).

If you are using them in conditions, then the data type is based on the left-hand side of the condition, so you might want to check and republish those as operators may change. It really depends on the type of conditions you use. Something like "field value matches [regex]" wouldn't be impacted, but a "field value greater than 500" might be since it would go from alphabetic sort to numeric sort. Though, with the field going from text to number, it's less likely you had the latter type of conditions.