Now I'll admit, this might be me just being butthurt, but I do think Johann's (and Roswita's) first Romance action got... gimped by two issues.
Like other people have brought up, this was a religious festival, rather than a more traditional date such as a dinner. This not only changes the context around it, by giving it a more formal tone and such, but the "Romantic" aspect of the festival is one that Boney wouldn't explore since having "It's apparently an unspoken tradition for courting couples to venture into the mines together and return with a suspicious lack of ore." Come up as anything besides an awkward conversation would be a massive leap forward.
It also as other people have said, brought more word focus on the cultural event that was happening, Which makes sense it was a very interesting bit of world building, which I did enjoy, but it did take up space, and it did take a bit of the focus away from Mathilde and Johann, compared to the explicitly one on one nature of Panoramia's Dinner date. For example:
Perhaps not the most romantic setting, but that might just be a matter of perspective - it is a religious obligation to leave your fellow miners be unless they're actively threatened by enemies or cave-ins, even if the sounds coming out of their side branch sound nothing like metal on stone. It's apparently an unspoken tradition for courting couples to venture into the mines together and return with a suspicious lack of ore.
You're not sure if Johann knows about that part. You went forward on the assumption that he didn't, otherwise asking to join him for this would have been even more awkward than it was.
One thing I've seen brought up is how much Mathidle fretted over the Panpan date. And while I'd love to bring up this as a counter example, I can't, because I don't know if this was a "Pre Date Nerves" or if this is "Inviting yourself to Your Friends Church" thing. Whereas Frankly I imagine, if we had selected the Johann physical fitness option instead, then that sort of thing would be much more obvious.
I could bring up some of the same points about Roswita actually, The fact that we went to an event with her , rather than date, I feel really did , cut into the amount of time dedicated to her and Mathilde's interaction, as more of it had to be dedicated to the event, compared to say, the boat trip.
And secondly, I think Johann's date was affected by something no other date will be affected by. It served as a bookend to the two of them starting off the reclamation with the gas mask. Which don't get me wrong, it was a very important and well done scene, but having it serve as the end of the Date, did make it feel like the date ended on a discussion about work, rather than personal interaction between the two.
Narratively that sort of acknowledgment needed to happen. But personally I feel like it should have happend at some other earlier point. Not during the first Tentative Romance action.
Though to give Boney credit, we do still see signs that they can banter:
"I haven't noticed any dust," Johann says with a smile, and you wonder if his Magesight can see enough to notice someone rolling their eyes at him.
And we do still see signs of how they get along in a more serious sense:
"Better to do one thing well than be mediocre at everything," you say. "My Master told me that, then got annoyed when I skipped Diplomacy class."
He gives a brief laugh. "I suppose you're as typical a Grey Wizard as I am a Gold."
But, to me anyway, those seem to have been overshadowed by BoneyM's world building. Where a more personal situation, would have been more... personal.
TL;DR: I think Johann was outshined by worldbuilding, and I hope he can get a more Date like setting to try and shine.