Yes, the RM library opens in RM, and I can use it just fine back and forth with Word. It’s fully functional, except for being unable to convert to EN. However, this library is several years old and has gotten corrupted at least once before. RM seems to be buggy in that way.
I just copied all the refs in my problem RM library into a new RM library, which then converted to EN perfectly fine (and yes, the RM fields that I use align just fine with EN fields). So – I think my problem is solved, since I can now transition these projects to EN without having to recreate the entire library, which is a relief. And now I know what to do next time one of my RM libraries proves too stubbon to make the conversion!
Thank you for your help!