When attempting to submit a wildcard A record, an error appears:
me@gw01# set service dns forwarding authoritative-domain example.com records a * address '10.0.10.1' Invalid value Value validation failed Set failed
The same happens for AAAA records.
me@gw01# set service dns forwarding authoritative-domain example.com records aaaa * address 'fc00::1' Invalid value Value validation failed Set failed
This is part of DNS spec and should probably be accepted.