I think the problem is that you have the new fields inside the phrase tag, as phrase parameters. You could actually do that if you wanted, but you'd have to edit the phrase and add {3}, {4}, {5} where you want the new fields to show up.
But the easiest thing to do would just be to move them outside the phrase curly tag like:
Code:
<p>{vb:rawphrase welcome_to_our_newest_member_x, {vb:link member, {vb:raw newuserinfo}}, {vb:raw newuserinfo.username}} {vb:var newuserinfo.field12} {vb:var newuserinfo.field14} {vb:var newuserinfo.field11} {vb:var newuserinfo.field15}</p>