I don't like offendo for falter.
If you showed me your translation without any context, I would take it as "Although I am offensive [to other people]"; if I look at the Lewis & Short entry you quoted from, the examples there all involve the context of other people in relation to whom a mistake is made or some abstract thing as 'the law' (with the exception of the ecclesiastic example). That doesn't quite convey the meaning of the English word 'to falter' (except, maybe, the ecclesiastic take on it).