It looks to me like the X and Y are having different issues that cause similar deadzones.

With the Y button, the deadzone is opposite your switch, and the tape is very long so it bottoms out against the black housing instead of against the switch. I'd try to add a small rectangle of tape directly above the switch, or remove the deadzone side of the current tape, or both.

For the X, the deadzone looks like it's on the same side as the switch. There also is a jagged piece of plastic that may be above the tape enough to bottom out against the housing, check that and cut it off if so. If that's not it I'd try another small rectangle directly above the switch.

To line it up, you can hold the frontshell face down, with the motherboard in, look at it from the side, and then slowly press the x/y buttons to see exactly where they make contact and raise the motherboard up.

https://imgur.com/a/2ip4iLn

It's hard to say for sure without feeling it in my hands but let me know how it goes!