Here are some issues I encountered during my hell mode attempts:
1. Moony (Huge Breast, Wizard) seemingly does no damage with their ability. It also says "Knocking them up for 0.5 seconds" but the stun can't proc since the ability can't hit.
2. The reward to "Choose an XP (trait) type and receive a bond proof (trait changing item) of that type plus 10 gold" doesn't give you the proof.
3. Occasionally you will get the victory proof (+1 girl slot) from the 3 random proofs reward. These can sometimes not provide the extra slot.
4. Meina (Maid, Archer) also seemingly does no damage with their ability. I only noticed this because a 2 star Meina doesn't beat the 1 star Lira in round 1.
These issues have made some units completely useless and makes the early game very forced. The only units really worth picking up in the first 3 turns are Lira and Mei.
Even with these issues the game is still fun enough. Hell mode is in a bit of a rough state in terms of balance, but here's hoping you continue to update the game to work out the kinks.