I'm looking at https://tools.wmflabs.org/guc/?by=date&user=Pil56-bot . This bot is working right now on it.wp as I write, but the page only shows edits starting on May 12 ATM. The query seems to work just fine for human accounts, like my work one.
Indeed. GUC has no caches or delays, it shows the latest information coming directly from the wiki database's replica available to Tool Labs. That replica, however, can sometimes be a few seconds/minutes behind the live database. This applies to all tools.