The tag implication #66788 rath_wyvern -> flying_wyvern has been rejected.
Reason: I've come across a post with a rathian not tagged as a flying wyvern, although properly tagged as a rath wyvern. I went to dig a little deeper, and it seems that rath_wyvern does not in fact imply flying_wyvern, even though the tag (encompassing rathian and rathalos) is indeed only used for flying wyverns.
HOWEVER, rathalos does imply it properly. I believe I heard something about recursive implications not supposed to happen, so if this should instead be done through a BUR that also removes the direction implication from rathalos to flying_wyvern, I can correct this (but there's a few more recursive implications in the more granular tags for these as well)
EDIT: The tag implication rath_wyvern -> flying_wyvern (forum #441452) has been rejected by @Bugabond.
Updated