Support Text Fields in JSON-LD Templates
Text custom fields in structured data templates
Problem: the JSON-LD template accepts only Select fields as variables. Text fields (author, ISBN, address, phone) can't be used, so key schema properties stay empty or render as unfilled placeholders.
Proposal: allow every field type in the template, and drop the property when the value is empty.
Workaround today: leave those properties out.
Pending