Not really happy with this translation. Fix as needed.

半人前 is a term related to 一人前 and has a meaning similar to novice, newbie, or in-training in contrast to the latter term. Granted, it's likely a term chosen to point out Youmu's heritage as well, but that is secondary.

Youmu's first line is a bit perplexing but I think it's best to leave the original ambiguity. Changed accordingly.

Isn't it usually translated as "half-baked" when it's about Youmu? Of course, "hey, half-baked" sounds a bit awkward...