1. Ver 15.0.2
2. Create fillable form in InDesign and export as interactive PDF.
3. Form tags should be nested inside (for example) paragraph tags. Alternatively, Form tags should display "BLOCK" placement attributes in PDF (Tag Properties>Edit Object Properties>Attribute Object Dictionary).
4. What actually happens is neither of these. Form tags are exported inline with other tags but without the BLOCK placement attribute. According to Matterhorn Protocol, these are not appropriate semantically for the structure element "Form." This is a PDF Accessibility issue.

What I end up doing is taking each Form tag and nesting it under the descriptive P tag which precedes it. This is time consuming and could be automated.

I would suggest either making this a default behavior or offering an option in InDesign's Object Export Options to set the BLOCK placement attribute. This would also frequently come in handy for figures or images that are placed as block items.

Thank you!