Exactly how I recall things, running english only applies to how contact with a rail affects the cue ball's path.
Dealing with the OP's question, he needs to do a little reprogramming on his brain. Outside english is harder for him because he has decided it is. He can as easily decide it is easier, just some mental gymnastics involved. Outside english is more honest in this case, the object ball will be mostly affected by hit angle without the affects of spin or throw changing the angle of the object ball's path.
With outside spin I would ignore the effects of spin and focus on the hit angle. With inside spin on this shot I would compensate for spin when striking the cue ball.
I had the idea that inside english was harder to pocket balls with a few years after I started playing pool. I deliberately round filed that idea and a few more I held that were holding my game back. Once I quit dodging "difficult" shots as generic groups I found that they didn't exist or the degree of difficulty wasn't that greatly increased. My skill level in a tournament opponent's mind greatly increased when I casually backcut a ball early in our match. The keys to back cutting balls are simply to find your spot on the object ball and hit it. If it is a significant backcut I always take a quick walk to get a closer look before shooting the shot.
A little derailment but hopefully some helpful advice. Throw out the idea of hard and easy categories of shots. This is something lurking between your ears more than fact. Once you consider it fact, it is fact until you uproot it though. As many a great instructor has said, much of pool is played between the ears. Whatever you accept tends to become your truth.
Hu