This category of question is on topic.
Stack Exchange's Q&A doesn't just take the form of question and answer. It also takes the form of problem and solution. This principle is why our topicality help says “You should only ask practical, answerable questions based on actual problems that you face.” It's also the principle that allows frame challenges to exist: they come from a place of solving the problem over answering the question.
This means RPG.SE isn't just about people asking arbitrary questions and getting answers. It's about them expressing their problems to us, and us solving their problems as best as we can manage.
Those questions fit into this format pure and simple:
- Problem: I'm not confident I understand this thing correctly. I'd like to express my conception to you and have you verify it, or correct me if I've misunderstood.
- Solution: We address their level of understanding to confirm or deny whether it's accurate and help them understand, such as by making corrections or re-explaining stuff.
You could think of this as variation on “How does this thing work? Here's my research,” but where their research has already gotten them ≥90% of the way toward understanding things.
Whether the individual questions in this format are any good is a case by case matter, but the basic format of “confirm my understanding” is unequivocally on topic here, and we've been handling questions along these lines since forever.
Even if we were to just examine this only in the lens of Q&A and not problem-and-solution, “is this solution valid?” is definitively a question that can be answered, and that it's about validating something is neither here nor there.