It's not just him. I'm a British English speaker and read it the same way. I read it as "We are far [along our course]". It came across as a bit of an odd phrase but I don't think it's really good English either way, it needs an object to be clear.
The problem is nobody ever says "we're really far". It's either "we've gone really far" or "we're really far away".
It's almost gramatically incorrect to say "we're really far", unless it is a response to a question - "how far are we from home?", "we're really far". In that case it works because the subject is implicit.
It's like you can't have a title that is "It is the best smartphone yet."
"we are far" to me means "we are distant (from the objective)"
https://en.wiktionary.org/wiki/far#Adverb
If it was "far ahead", or "we've come far" I'd agree with you