It seems like seedpicker doesn't support other languages.

[ezxpro]

I tried some seedphrases in the BIP39 standard word lists and it seems like no other language besides English is supported.

That should be fixed, I think, because other languages are part of the standard too

[ezxpro]

actually, I see the seepicker code has all the other languages in it, but still, when I try to process a checksum out of a BIP39 phrase that's not in English, it tells me all the words in that phrase are absent in the wordlist, indicating it just looks into the English wordlist.

[merland]

Thanks for the suggestion. It is true that SeedPicker does not support other wordlists directly. This is a deliberate tradeoff, to not complicate the user interface with a feature that very few users want or need.

There is a workaround though. All seed words are really just numbers, so you can "translate" any non-English seed word to English by looking at the number of each word in the respective word list, then run the corresponding 23 English words in SeedPicker. Finally, you translate the generated 24th word back to the original language.
For a double-check of the resuIting seedphrase I would recommend Ian Coleman's BIP39 site.