AHHHHH! You are all the best. I appreciate your help and I'm sure my orchids will, too.
I think you're absolutely right. And it sure does look like Sweet Sugar. I looked up Oncidium Shonan X Oncidium Kaizumic Delight and I found a couple photos that look a lot like it too!
And, yes, I overwatered it.

I'm not quite sure how because the orchids around it seem to be doing well so far and one of my very happiest orchids grows like mad and has bloomed twice this year in the same kind of pot. Different species, though.
Except for the cymbidiums, I always water the rest of the orchids on Sunday and *sometimes* if it's especially hot or dry out I'll water them a little some time during the week. Almost all of them are planted in Miracle Grow Orchid Mix which is very chunky and 'barky'.
Unfortunately, when I repotted this one, I experimented a little and added some of the other Miracle Grow orchid mix which is very fine and dense. I wonder if that's partly where I went astray. I thought it might like a mix. N00B.
SO... I just unpotted it. I'm attaching a photo. The dark roots aren't mushy and are firm but don't look good compared to the roots that were laying on top of the soil.