I think you could create a new topic with the question “How do I convert my PDF to PDF/A-1b?” if you need help converting your document to PDF/A-1b, or directly create an issue on Issues · typst/typst · GitHub with a feature request for PDF/A-1 support to discuss that particular bit.
Technically speaking, there is no requirement to “upgrade” from PDF/A-1 to PDF/A-2 as there is no succession. PDF/A-2 does not replace or supersede PDF/A-1. I can find well-known institutions asking specifically for PDF/A-1:
- MIT: Saving Your Thesis as a PDF/A-1 - MIT Thesis FAQ - LibGuides at MIT Libraries
- Warwick College: PDF/A format for final thesis
- Memorial University: Thesis Help | Mathematics and Statistics | Memorial University of Newfoundland
In any case, I feel like this topic disgressed too much probably. As said above, it might be good to split it.