So this is the question I tend to ask, if nothing else to learn something about your tool. Why should it use it over more established competitors? I am specifically thinking something like Roll20 and FoundryVTT, the former being easily accessible and free with SRD content at your fingertips, and Foundry just being, well, Foundry. Hell even Owlbear Rodeo for a generic and easily accessible tabletop. For campaign management text programs like Notion.so and full on world managers like World Anvil are providing massively powerful tools too.
What it is Dungeon Maker provides that is either missing from these other options and is so useful that losing out on all the other stuff in them is worth the switch, or what does Dungeon Maker do so much better than the others that it is worth switching?
Not trying to be a jerk about it, it looks like you have a solid base, just curious about your ideas on these things.
The Bard player still has to say the right things in the first place to make the check at all, there is not guarantee they will do that. But if they do… LET THEM this is literally their characters big thing! Why not let them do that specific thing? It feels backwards to me to have a “Well this fight has a conversation skill option but I am not going to let the character that has conversation skills participate”.
IMO the rolls are not the interesting part of this, the party figuring out how they can get bad the guy to change their mind is.