Special Cactus looks wrinkled and is getting worse

[keithp2012]

I have a variegated gymno that was shipped to me from another country. 75% is yellow/albino and 25% is normal green. The green side is looking good, but the yellow has slowly been shrinking and getting wrinkled and some tiny white lines, I think it might be too much light burning it due to its color. Yellow side is slightly soft green is hard and firm. This cactus has tiny roots.

I have been putting it in water to soak an hour a day thinking the tiny roots aren't getting water fast enough from the soil before it dries, plus sun indoors might be dehydrating it. I say this as no brown rot is visible and the tiny roots plus lack of color on most of it probably has the poor thing drying up quicker than normal. But being it has tiny roots I can't overwater either.

Any thoughts?