First off, thank you so much for the kind feedback! I'm sort of beaming with pride that you've stuck to these sheets through their many iterations (I know I keep changing things!), and I hope that you continue to find newer versions to actually be improvements over older ones. That being said, if you haven't tried them yet, please try the v7's and let me know what you think! Those are a really big overhaul, and I'm considering moving in that direction if it is indeed an improvement over the current "Classic" version. Also, thanks for making an account just to contact me; that's a big step to take, and I appreciate the dedication to communicate both your feedback and issue.
Regarding your issue: I downloaded the fillable form straight from the website and opened it up in MasterPDF editor, and I cannot reproduce your copy-paste issue for the Traits section. It seems to work without issues on my system (Arch Linux + MasterPDF editor), which makes it difficult for me to identify what needs to be fixed/changed. Your pdf editiing software should totally let you save the filled form without having to fill everything out- that's crazy! I would suggest Foxit or Adobe Reader if you're using a Windows system, and Adobe Reader if you're using macOS. Try using one of these other softwares and let me know if your issue persists.