While people who have studied those periods fully would probably be distracted by the anachronisms, I would forgive the use of seconds and modern units of measurement for that same reason, that it would make it easier for the reader to stay with the book rather than having to look it up.
In reading some ST:Voyager fanfiction recently it reminded me of another pet peeve, when you can't tell who is talking in a conversation. I can't remember an exchange at the moment but it's usually something like this:
"I better get to the medical bay" The Doctor said to Captain Janeway.
"Seven is wanting to work on her bedside manner."
"I guess I'd better get going then, don't want to be keeping her!" And with that, the Doctor beamed to the medical bay.
Now all 3 sounds like they could be said by the Doctor, but the way it's written with each quote on its own line and knowing he was talking to the captain, it could be her saying one of them, but who can tell?