Reference variable in Form Text element


I was wondering it this is somehow possible, that I could prepopulate Form Text field with some already exsiting variable value (like process variable)?

This seems to work with Expression (actual value is displayed), but not with Text (it displays given expression as a plain text), I tried this one:
where client_firstname is process level variable.


Looks like I made it. The trick was to use the same ID for Text element as the name of the variable, this way value gets pre-populated just fine.
Don’t know if this is 100% valid solution, but works. For me this is enough. I would appreciate other comments or solutions though.