The Spool Java Transformers 14.0 documentation contains the following information regarding the PDF/A generator:
PDF/A Generator:
Generates Adobe PDF output that is compliant with the PDF/A-1b (ISO 19005-1:2005) standard.
Are there any plans to implement generators for the PDF/A-2 and PDF/A-3 standards?
Spool Java Transformers 14.0
The generators for the PDF/A-2 and 3 formats are in the roadmap of the Transformers vendor for future implementation. At this time (March, 2024) there is no exact timeline for this implementation.