I don’t know if anyone at AppSheet is actually tasked with monitoring the community for bug reports. I am not tasked with that, but do so because it seems like something I should be doing.
When I see a bug that seems to be or has the probability of being a major problem, I’ll “escalate” it internally by reporting it on an internal chat group that most of the technical staff follow (it seems to me). When I respond with “escalated”, it means I’ve mentioned the issue in an internal chat.
For issues that seem less severe, or that seem to be edge cases that I suspect will need deeper investigation, I’ll recommend contacting firstname.lastname@example.org. The Support team (which may include developers) can then ask for whatever other information they need. In your case above, I’d expect development will want access to a sample app that reproduces the problem.
Other than email@example.com, I’m not familiar with other means to engage support or report problems. My sense is that this #bugs-issues-errors category is not a particularly formal channel–but I may be mistaken on that.
In general, my own personal guidance is to contact firstname.lastname@example.org if the issue is urgent, complex, or you feel you’re owed a response because you’ve given AppSheet money. Use the community if you have time to wait longer for a response, are looking for a workaround rather than an immediate fix, or just want to make others aware.