I really recommend an EXISTS statement for this, as you're looking at a lot of "hops" (what Workfront refers to as "levels"). Specifically you need to go (hop) from the task level, to the project level, to the sponsor level, to discover that sponsor's homegroup. If you say "traditionally, workfront filters can only go to 2 levels" that third level is currently inaccessible to you without an exists filter.
https://experienceleague.adobe.com/docs/workfront/using/reporting/reports/text-mode/create-complex-t...
Take a look at this sample code below.
EXISTS:a:$$OBJCODE=PROJ
EXISTS:a:ID=FIELD:projectID
EXISTS:a:sponsor:homeGroupID=$$USER.homeGroupID
EXISTS:a:sponsor:homeGroupID_Mod=in
How it behaves in a TASK report:
Line 1 - look for all the projects
Line 2 - where the project's "ID" field is the same as your task's "projectID" field
Line 3 and 4 - for these projects, anywhere where the sponsor's homegroupID is equal to the wildcard for the user's homegroupID
Lines 3 and 4 were copied directly from a PROJECT report. (i.e. I figured out the text mode for this in a project report, and copied it over into the task report's exists filter). I think a lot of people need to understand this part more -- it's pretty critical for successful use of text mode after you have done lines 1 and 2. The first two lines basically unlock the ability to use the textmode from the OBJECT you just linked to. Above - the first two lines link you to a project report, so if you can show a list of projects to a view based on their home group, you can now do the same for a list of tasks.
