I’d say that not doing it is forgivable, but doing it definitely looks better. So it depends on how much energy you want to dedicate to polish.
There’s a lot more tolerance in English for technically-incorrect noun pluralisations than there is for incorrectly-conjugated irregular verbs, say: it’s much nicer to use the correct plural, but if you’re that guy who corrects the other players every time they say ‘okay, roll a six-sided dice’ then you’re being a pedant.