Contrary to the "There is no validation for variable values based on the field settings" text, the Update Variable Value screen does attempt to validate input to numeric fields.
The input mask applied here creates difficulty entering valid values, though. Attempting to enter "0.5" is entirely unintuitive, for example. The field suppresses attempts to start with "0", displays an error when starting with ".", and clears itself entirely when attempting to follow the "." with a numeral. It will allow you to enter "5", arrow left, then add the "0.". It will also allow pasting the complete "0.5" from the clipboard. It will not allow entries without the leading zero.
Laserfiche Forms Professional Version 11.0.0.537