teor:
I've looked at the Tor source code that handles versions. Version parsing and voting seem to happen unconditionally.
I also checked router_differences_are_cosmetic(), and it seems to handle platform string changes correctly.
I'll need to read a spec to know what "correctly" exactly means here.
So maybe the issue is in the descriptor fetching and updating logic? How many authorities received the new descriptor? Did any of the other fields in the vote change when the new descriptor was updated? Can we get logs from the relays that are affected by this issue, so we can see how many authorities they uploaded to? Can we get logs from some authorities so we see how they handled the new descriptor?
I'll collect affected relays on the trac ticket.
It might also help to open a core tor ticket to track this
https://trac.torproject.org/projects/tor/ticket/24864