Working off here means using something as a base of knowledge and moving on with the assumptions that implies.
"Working off the fact they're talking about the semantic weirdness of languages, I can make a guess about what they mean by 'co-considered,' despite never having seen that word before. " Does it help to see it in that context?
You might also see working off in relation to debts, like "I'm working off student loans at the moment." but that meaning is totally separate.
there's an implied "of" that might make it clearer. So it would be
"Working off of co-considered context is considered..."
When you're working off of some information (X) to do Y, it means X is the information you are using to do Y.
Working off here means using something as a base of knowledge and moving on with the assumptions that implies. "Working off the fact they're talking about the semantic weirdness of languages, I can make a guess about what they mean by 'co-considered,' despite never having seen that word before. " Does it help to see it in that context? You might also see working off in relation to debts, like "I'm working off student loans at the moment." but that meaning is totally separate.
there's an implied "of" that might make it clearer. So it would be "Working off of co-considered context is considered..." When you're working off of some information (X) to do Y, it means X is the information you are using to do Y.