Tangentially related to the variable lengths ...

If you have a label defined that has trailing spaces in the sample data, the ZebraDesigner may get confused if you change the fonts and update the label printing configuration.

Or it may be on load that ZebraDesigner drops the trailing spaces.

The resulting variable configuration is a string of 30 characters (including a few trailing spaces) with a length of (actual length + number of trailing spaces) does not print properly.  It breaks the line before one would expect and overlays the content from the break point at the beginning of the line.

Since I have a work around (restore any trailing spaces such that the length of the sample data matches the max character limit for the variable) I am not going to report this as bug, and hence am only submitting informal and unverified steps to reproduce the problem.

Create a label
Include at least one variable that has trailing spaces and the max length includes the spaces.  For example:

"SOME SAMPLE DATA    " ("   " = 3 spaces), set the max length to 19.  19 is the number of characters in 'SOME SAMPLE DATA' plus three (spaces)

Save the label
Upload a new font to the printer
Apply the font to one or more fields on the label
Now change the font
Export to printer, print test label
Edit the variable, add the three spaces back in.
Export to printer, print test label