Naava wrote://EDIT: shouldn't Welsh and Irish be in the same group?
The OP asked to sort translations by similar metaphors rather than language family. So your Finnish translation goes with the Irish. I've moved it there.
Adding two French translations. I decided to pair "take it with tweezers" with Italian's "take it with tongs", since the image is similar.
English: take it with a grain of salt
Dutch: met een korreltje zout nemen
(take it with a grain of salt)
Latin: cum grano salis
(with a grain of salt)
Welsh: ei cymryd hi â phinsiad o halen
(with a pinch of salt)
French: ne le prends pas pour argent comptant
(don't take it for ready money)
German: Nimm es nicht für bare Münze!
(Do not take it at face value!)
Greek: μην το πάρεις τοις μετρητοίς
(don't pay for it in cash)
Finnish: älä purematta niele
(don't swallow (it) without biting/chewing)
Irish: ná slog gan chogaint é
(don't swallow it without chewing)
French: prends-le avec des pincettes
(take it with tweezers)
Italian: prendila/o con le pinze
(take it with tongs) / prendila/o con le molle
usually means "spring"
, but I've found out that a secondary meaning is "tongs for the fireplace" and I suppose this is the intended meaning here)
N'hésite pas à corriger mes erreurs.