I agree with most here that this last arc of them really getting to Brant could have used like 10-20 more chapters (and at least a few of those dedicated to a juicier epilogue) but overall I think it was a lovely little manga. Really had a spirit that reminded me of MegaMan Legends, and I loved...
I know this is gonna resolve itself but I really hope they don't go "lol the power of friendship redeems all" with this guy because he literally tried to murder that kid and is generally the worst. Just kill that dude or banish him to hell or something.
i think "But you still are, right?" is fine and reads much more naturally than shounen twice. Even if you wanna consider it a nickname rather than her literally calling him boy/kid/lad/youngling/whatever she's still referencing that he still is the thing that prompted her to give him that...
I think the "Sure, let's go" was definitely for them going somewhere alone. He seemed to get it, asking for clarification was probably more from surprise than him not actually understanding, in this case.
I love that the romantic delays come from their own interpreting of their growing feelings, not shitty miscommunications, so once they're on the same page they just DO IT.