Probably thinking about it too hard myself, but here are some thoughts.
Upload and download infer a temporary, potentially unstable connection or a remote/temporary target.
Read and write infer something less remote and much more stable and consistent.
I think upload and download make the most sense for this use case considering protocols in use and the temporary connection or potentially unstable one.
Read and write might set expectations too high for some users.
I'm going to go out on a limb and say, from one over-thinker to another, I think you over-thought that real good :)
Looking at several other packages, here's what I find:
KC8UNJ Commander: Read/Write Kenwood MCP: Read/Write Kenwood Commercial: Read/Write Icom CS: Read/Write Yaesu ADMS: Get/Send CHIRP-legacy: Download/Upload
Sure seems like read/write is the more common thing. "Because Yaesu did it" is never a good reason, IMHO, so that's an easy outlier.
I think that means read/write would put us on par with most everything else. Anyone else have data points or opinions? Maybe some non-Americans with different connotations for those words?
--Dan