Hope you’re not waiting on me; there isn’t anything more I can contribute to this thread, sorry!
Maybe the shortcut on sentence does not fit well in english. Sorry. By “free to help”, we should read “I’ m free to help” (I am). “Feel free” was not used, so “free” as first word could generate an other misunderstanding. So, my bad.
The relationship distance will be called between one person and distant parents. We could set this person as a static, hardcoded or constant one, because it is the home one into the Family Tree.
Not certain that Relationship module takes care of private flag. Also, it only occurs with this dataset according to one default person and its relationships map (list of familles and relations). Some large graphs (gramps reports) have been attached either on the bug report or the workaround PR on github.
Maybe it should be possible to catch these “broken entries” by playing with filter rules (ancestors, descendants, up/down, etc.) before calling the relationships module. That’s also why I thought on a corner case, as there is some variables (dataset, relationships, distance).
Filters handling (managing) on the addon is not flexible yet (still hardcoded filter rule set). There is an environment, but still in progress because I did not find a built-in widget or sample into cur(r)ent set of core modules of gramps, which could fit well for such category of tool.