Yep, this works fine (in GoAWK, gawk, and mawk, though not in original awk):

  $ cat t.usv && echo
  id␟name␟age␞1␟Bob "Billy" Smith␟42␞2␟Jane
  Brown␟37
  $ goawk -F␟ -vRS=␞ -vOFS=, '{ print $1, $2, $3 }' t.usv 
  id,name,age
  1,Bob "Billy" Smith,42
  2,Jane
  Brown,37

I've also added explicit tests for ASCII and Unicode unit and record separators, just to ensure I don't regress: https://github.com/benhoyt/goawk/commit/215652de58f33630edb0...