Search sucks.
With that out of the way, I am using Native Outlook on Windows Server 2025 and CVAD 2507 CU1 with the Microsoft EnablePerUserCatalog Enabled and the Citrix Enable search index roaming for Outlook - Disabled.
It works most of the time, but not all of the time. The Search Index will get corrupted occasionally and we get errors in the logs.
I have a script that clears and resets the user search index folders for the logged in users and I rebuild the local index at the same time twice. I don't know why, but I have found that doing the double rebuild helps get the users to rebuild.
I haven't found a reliable method to automate that process though, if someone has one I would be interested in learning it.