There’s a new option in the match search: after you’ve selected the parameters of your search, you can hit “Opposition player statistics” to see the list of players who’ve played against Sydney FC in those matches. And once you get there, you can click through to see each player’s full list of those appearances against Sydney.
Examples: those who’ve faced Sydney in the ACL (Yuki Abe did for Urawa in both 2007 and 2016), for other Sydney-based teams (Nikolai Topor-Stanley has the most such minutes, with 1080), or in Sydney FC wins at the SFS (Andrew Durante lost 12 times there).