So this issue is invalid: it doesn't really make sense for macro parameters to belong strictly to same feature and group as those have different purposes. I provided a bit more detailed documentation regarding usage of groups and features in https://www.xwiki.org/xwiki/bin/view/Documentation/DevGuide/Tutorials/WritingMacros/WikiMacroTutorial/#HGroupsandfeatures
Note that while writing this doc I also found a limitation that I reported in XWIKI-24149
