r could have a quick sound from the tongue on top of the palate, resulting in a 'ch' ish sound
"she's" can be both "she is" and "she has", and Duolingo's system is naïve, so it occasionally gives out what is clearly not the best suggestion. :)
So, is there a singular common vs singular neuter vs plural distinction for all colors (or adjectives in general), or only some? I noticed I only ever saw "rosa" for both singular and plural nouns. Also, there were only two forms for black? (svart being used for both -en and -et words)
Yeah, some adjectives are just indeclinable, like rosa and bra, these generally end in -a, -e, -s. Svart remains the same in the neuter since you can’t have svartt.