> That's not SECDED, since it can't correct a bitflip that occurs somewhere other than on the link

You're just making up arbitrary rules. The term SECDED does not incorporate any guarantees about which part of a system it applies to. It's just a mathematical statement about the strength of the ECC in use plus the implication that detectable but uncorrectable errors are reported.

What you're looking for requires more words to fully specify, probably including the term "end to end".