"Since he's already successfully fulfilling his role as an anti-mage in lane, we'll be buffing him in a way that increases his general power without altering his matchups."
"Generally pretty weak and is countered particularly hard by some of the mid-range mages in the meta. "
So is Galio actually fulfilling his role as an anti mage or not
Galio generally loses prio to mage matchups in lane and that's intended. For Galio to actually beat these Champs in lane and get prio, his combat pattern would need to be pretty overtuned.
So we think his lane is fine; he loses push, but won't die and can farm defensively relatively fine.
Where he is intended to excel is in using his globals to impact the map, hence buffing that aspect of his kit rather than make him generically powerful. Sorry for the confusing wording there.