Is this possible ???
It is not, Likely as to prevent importing a cheated/edited character over.
While part of me wishes it was not the case for the longevity of the game its best this way even if annoying right now with the server issues.
If the OP didn’t spell it the wrong way, the OP means the other way around, that (potentially) can have an offline-backup from online character. Not the other way around that you can upload them.
it would be neat if you could clone your online character to offline. Different rosters, etc.
I don’t think there’s anything against this, but I don’t think there are plans either for making this happen. Should be low on priority, especially at this time.
As a last resort, you can simply create the character offline and then edit it to make it the same as online, though I’m not sure that is allowed by the ToS, so do it at your own risk.