Though of course, there's also the process of keeping all of the "strength bars" full.
If you type in "trial" to WordReference/SpanishDict, it does not list "proceso" as a translation. "Proceso" is closer to "process"
Ok. This is getting ridiculous. "The process is lengthy." means "The process is long." They should both be accepted.
Synonymous yes but they are still different words, Duo is trying to get you to learn the best translation.