Not sure if it’s relevant to your problem, but AppSheet caches the PDFs (in my opinion it should not, or at least do it based on time and size to indicate a change, which is what proper cacheing should do IMHO)
The cache lasts for a long period (too long!)
So when you generate the PDF file of the same name you get an old cached copy (A really bad user experience).
The way I got around this want to use a counter in the filename and hopefully, after 20 copies of the PDF the cached copy would not be fetched. If 20 is not enough I would increase it.
Using a time stamp on the file would build up a huge number of files that would cost a fortune in storage eventually.
The other annoyances (that have never been resolved) are the lack of headers, footers, and page numbers. Appsheet is a great development environment but lacks proper PDF processing suitable for business reports.