> Adobe publish Adobe Animate, which is the only professional, cross-platform tool for making Flash and AIR content
You get the Adobe Air SDK for free, so you can use any IDE/TextEditor and package you Air App without having to pay a single cent to Adobe.
IntelliJ is a very professional tool to write your Flash/Air stuff and is much (very much) better for coding than FlashBuilder, for example. For most projects I worked on (professionally) I did not use Adobe Animate or FlashBuilder at all. You can even use FlashDevelop or VSCode and get a very nice developer experience without spending any money on software at all
> I'm still not sure why google contacted the developer if they were sure its AIR.
Google does not have to be sure that AIR has a problem. All they do is to inform you that your app is not working due to a requirement which was not met. They don't care what technology you use. They are not allocating any resources to resolve the issues you are having with the software stack you are using (unless it is a official supported stack, I guess). I you want keep using AIR it is your own responsibility to resolve technical issues with Adobe. I would argue to expect more is very wishful thinking.