Why SA form Kayn is going to be difficult to balance, and an easy fix

Right now, SA form Kayn is generally considered the worse form, and the one that you should avoid at all costs. While i feel like part of this is just because people haven't learned the champion yet and are still trying to get the hang of him, and Darkin form is much more forgiving and easier to play, but I feel like there's a legitimate reason why SA form feels weak, and why buffing him up would probably make him too strong. The problem is two things.

1. Unreliable escape. Right now, if you use your E to get into a fight, you really lack mobility to escape. Maybe with a well placed ult, but you probably need to use your R to dodge a spell or to finish of your target, so that's simply an unreliable escape.
2. The slow immunity on E is completely useless. Compared to the %damage and CC that Rhaast gains on his versions of the spells, The movespeed on E is nice but not too good, and the slow immunity is complete trash. For one thing, it only happens in walls, so you can't use it in fight to block slows. But since you are in a wall, any damage will cancel your E and most slows tend to have some kind of damage attached, so that's worthless.

I feel like there is an easy fix to this though, so I'll put the changes to his kit down below.

E: Being in combat no longer stops this ability from getting a longer duration. Removed slow immunity and extra movespeed is disabled while in combat. R: No longer refreshes passive, instead, for every second that you are in the R, it decreases the cd of every non ultimate spell on your kit, by a percent. So that if you wait the full duration, it refreshes all of your cd's including your passive magic damage.

Let me explain. The R now refreshes your cd's if you wait in it. This might seem broken, but think about what spells are going to be coming up. Your passive is already refreshed, the cd on your Q is so low that it would already refresh if you waited the full duration, and the W would be the same except you'd have to wait half a second before you can cast it. The only real spell that you gain is your E, which you can finally use for an escape. This kit change would also promote Kayn being riskier and waiting the full duration of the R if he wants the most out of his cd refreshes.