It seems like a great idea, but the execution is bad.
You can just go directly to ChatGPT and ask it how to make a formula for Excel or Airtable or a Regular Expression that does what you need. I was attracted to Formula Dog because I thought it might be simpler to go through an interface that is optimized to ask those questions. That isn't the case. There is no optimization or pre-training of the AI that gives Formula Dog an edge.
Furthermore, there are three major problems with Formula Dog. First, the formulas you need the AI to provide are probably the more complicated ones. For those, you will almost certainly have to engage in a back and forth with ChatGPT a few times to refine the formula to get it just right. That is easy if you go to the ChatGPT website. You can tell the AI to refine the formula it just gave you. It has a memory of your conversation. Formula Dog has no memory! You have to reenter everything again, and then try to figure out what subtle change to make to your query to get the exact formula you want.
Second, the answers Formula Dog gives are sometimes incorrect! In two of the experiments I did, it left off information from its explanation of a formula, or the formula it provided was wrong (because I didn't yet realize that it had no memory).
Finally, there is no support. They never got back to me about my questions.