UASM64parse.dll parses the functions, structures, objects, constants and other stuff and puts them into the listbox bottom right from what i remember. Also it was recently modified/updated to ignore the FRAME keyword in PROC when parsing procedures and parameters and a few other things like the 64bit registers to bring it up to more modern standards. Helps with the auto-completion of functions prototypes when using Invoke and looking in the appropriate .api file.
Not sure what the code templates and ct files are used for, dont know about the stdlib stuff either.
I would rename UASM64parse.dll to MASM64parse.dll and place it in the addins to support the MASM64 addition to RadASM as it should work just fine for it. Edit - I see that you have that already, so thats good.