Yes, and it reported 80 erorrs on the RX3 package and then 74 errors when I copied over the newer RX4 package. One or two I might be able to handle, but not that many. If only I knew just the right thing to do perhaps I could finesse it (that remains plan C for me) with some code or other changes, but that is a very deep dive to do right. Plan B is to ask here to see if anyone else has run into this, and Plan A is to keep Googling to find the people and comments that helped me get it working for Delphi 10.4.
Sincere thanks to everyone for looking at this and making suggestions!
Rob C