I ran the first four books of both Runelords & Shattered Star in one campaign in 5e; PCs went from 1st to 18th though only one was there for the whole thing. http://smonscurseofthecrimsonthrone.blogspot.com/2017/10/ep-64-22-3064713-ar-on-mokmurian.html
I don't recall any major issues - some boring static dungeons in Shattered Star, especially Book 4. The PF stats convert to 5e very easily, and 5e has far fewer I Win buttons. About the most I added was a couple of summoned owl bears to the final battle with Mokmurian, mostly an excuse to use my owlbear minis!
I generally increased hit points and damage by +50% from Pathfinder numbers, while AC was typically divide by 2 & add 5.
I've used a few converters, but it takes a while and actually I've found re-skinning existing monsters to be fun and quick. For example the Wyverns in Fortress of the Stone Giants were swapped with elder shadow drakes from tome of beasts.
I'm finding the AP a bit too combat-oriented for my taste but to be honest my players (mostly) prefer that.