Yes I think trying to coach up sweet spot% or launch angle is way too hard. It's basically trying to coach up HIT TOOL.
Certain guys may be able to deploy tricks to change their launch angle, or fix their mechanics, or alter their swing plane a bit. But many (most) these days won't be able to meaningfully change it intentionally because they won't have the barrel control to do it.
A lot of the famous examples of guys increasing their LA and pulling the ball more for homers are really, in a fundamental way, examples of players who were already pretty good hitters (in a basic sense - HIT TOOL) before making the changes. Justin Turner - was hitting for average and making contact before his tweaks so the barrel control was already there. Jose Bautista - had good PD stats before the changes and obviously had a good hit tool in hindsight.
There has been some semblance of the Blue Jays trying to take guys with "good hit tools" and coach up power. Clement, Horwitz, all the minor leaguers like Roden and Jimemez who don't have good raw power grades. Kirk.
But the Jays are probably 5+ years behind the eight ball, yet again, because other teams are already looking at things more specific and granular than "hit tool" as MikeM says they are looking at VBAs and stuff.
This might be why the Jays have a certain collection of organization guys with "good hit tools" but there has been a general failure to coach up or develop any power. They have the general idea right but are getting lapped or outcompeted on the specific implementation of it.
Hit Tool - old school scouting concept, define it how you want. some would say bat control. some would like at K% but that's very indirect.
Launch Angle - objective, measurable but not necessarily that helpful in all circumstances. THIS IS AN OUTPUT.
Sweet Spot% - objective, measurable. THIS IS AN OUTPUT.
Hard hit% - objective, measurable. THIS IS AN OUTPUT.
Barrels etc (some combo of hard hit and sweet spot or LA) - objective, measurable. THIS IS AN OUTPUT.
VBA - measurable, THIS IS AN INPUT.
Bat speed - measurable, THIS IS AN INPUT.
Biomechanics - measurable, THIS IS AN INPUT OF THE INPUTS!!!
What do the Jays look at? What do the best teams look at? To be ahead of the game you need to find the significant INPUTS. If you look at outputs you are probably lagging.