One thing that may be different (I'm not sure) with current generation printers, compared to older generations (and perhaps applied to older generations via firmware changes?) is:
It is not clear exactly when downloaded PCL5 forms are removed from memory; on my LaserJet Pro 400 Colour MFP M475dn, downloaded fonts (and, I suspect, macros), even if marked as 'permanent' (in PCL5 terms) do not appear to survive after the printer enters 'sleep' mode.
On older generations, 'permanent' objects would remain in (random access) memory until explicitly deleted, or replaced, via PCL control sequences, or until the device was turned off.
If you could capture a small (sanitised data) sample job (using the 'print to file' option in the Print dialogue, or equivalent (if any) exposed by your application), then analyse the resultant .prn file, it should show how 'forms' are being used.
You can post the .prn file here (you'll have to add an extra .txt extension to the filename in order to attach in this forum), and I could have a look, or analyse it yourself using the PRN File Analyse tool in the PCL Paraphernalia application, available via http://www.pclparaphernalia.eu