Usually, I focus on one until I finish the course, and then I move on to the next, while periodically reviewing the languages I've completed. And yes, I do occasionally mix up some of the words, but it is usually only Dutch<-> Swedish. Also, sometimes I will forget a word in English, and say it in another language.
I was using the question type where you tap the words (I'm on app) and it included an option for both spellings. I assume they accept both of these.
I would guess "kolorblindeco" would be colorblindness. The suffix "ec" is usually used on adjective-roots to give it that "ness" quality from English. Like "ruĝeco" is redness, etc.
This is why includification, and groups like AbleGamers, are important. People with various disabilities (audio, visual, kinesthetic, processing, etc.) can play many games with certain accommodations, such as visual cues paired with audio cues, or colorblind mode so that players aren't stymied when the red enemy markers and green friendly markers look exactly the same.