I tried "The elder tends to forget" and it was counted wrong with a bubble saying that "elder" means an official in a church. I can't be the only one who thinks of "elder" as a nicer/more polite way of saying "old person"?
Elder, as a noun, absolutely means more than just a church official. I'd bet actual money that's not even the most common use of the noun elder.
The current American euphemism is "senior" as a shortening of "senior citizen" to avoid saying "old person."
"elder" was given as the suggested translation the first time I saw "maljunulo". DL still doesn't accept "the elder" here. It bizarrely suggests "The old 1". I couldn't bring myself to put "1" like that, but it accepted "the old one". I'll try "senior" next time, as @drownloader suggested.