The library branch sorting on guarantor_search.pl is incorrect. It's displaying as Leavenworth... Carbondale... Prairie Hills... Lyndon... and so on. The sorting behavior is the same as what was reported and fixed on this bug, https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=13950, if that helps resolve this one more quickly.
This will be fixed by bug 15758. It may be useful to provide a patch for 3.22
I can confirm it's fixed in recent versions!