Hey TTim,
I know exactly what you mean and this is an area of my game that I find my weakest side to. My forehand side I feel alot more comfortable as you say to. I think the best way with the backhand is to make sure you’re behind the ball and go for a controlled backhand topspin stroke. Work on developing the feeling of playing your backhand against a variety of long serves. A common error is players rushing and taking the backhand to early, this causes players to mistime the ball.
Ideally if you are able to spent 15 minutes, 3 times a week practicing this against different players, your serve returns will improve very quickly.
When a player does the fast serve to your backhand, are you struggling with any sort of spin? Or is it the pace that’s making it difficult? Have you seen this video: https://tabletennisdailyacademy.com/videos/return-tricky-long-sidespin-serves/
If you can send in a video of yourself returning some serves from the backhand corner this will help us provide feedback
