I've added a client-side fix for this issue into the Stack Overflow Unofficial Patch v1.10. Alas, I have not been able to test it fully under "natural" conditions, since I don't actually have a four-digit helpful flag count on any SE site, but it does work as expected if I kluge it to artificially inflate the count.
In case you're curious, here's the code:
var links = $('body.user-page #user-info-container a[href^="/users/flag-summary/"]');
SOUP.forEachTextNode( links, function () {
this.nodeValue = this.nodeValue.replace( /[0-9]{4,}/g, function (digits) {
return Number( digits ).toLocaleString( 'en-US' );
} );
} );
Note that, since the fix is based on Number.toLocaleString()
, some older browsers might format the number according to the user's selected locale. All officially supported browsers should respect the explicit en-US
locale I'm specifying, though.
Edit: It seems the original fix caused some minor formatting breakage for moderators. SOUP v1.10.2 uses the updated code above, which should be more tolerant of the link(s) containing more than just a simple number. Thanks to Monica Cellio for reporting this issue!
Update: As of mid-2015, it seems that this issue has been quietly fixed at some point, presumably as part of the general user profile overhaul carried out in spring. The client-side hack described above will thus be retired from the next release of SOUP.
 
is the one true thousands seperator! U+2009 2014.