I just realized that BIP-0039 is language dependent. I was assuming the other way till I looked closer. The way the seed is derived from a BIP-0039 entropy, as is shown below, depends on which language to generate the mnemonic sentence:

Therefore when a user choose a non-English mnemonic code he or she is stuck with that language. Meanwhile only a few native languages are supported.

SLIP-0039 does not solve this issue in a user friendly way by providing only an English wordlist. That's understandable as it aims to provide SSS capability. However those users who do not speak English or recognize English words will suffer. 

What I am trying to bring to attention of the community is that, no matter if we make a new version of BIP-0039, or a new BIP (with SSS support), or to enhance SLIP-0039, we really need to address this language issue. 

Here are what I propose:

1. The mnemonic code should be only a representation of underlying entropy or (pre) master secret, seed, whatever. In this way, the same seed/secret could be displayed in English or in Chinese or other languages. Then there could be 3rd party conversion tools to support translations in case any wallet software or device does not support all specified languages. Now it looks like:

   Mnemonic Sentence <=> Entropy => PBKDF2 => BIP-0032 Seed

2. Given that only 8 languages are supported in BIP-0039, we should allow the seed/secret to be represented in decimal numbers, each ranging from 0 to 2047. So those who cannot find a native language support yet having difficulty coping words in other languages could choose to just use numbers.

So far I don't have a preference how this should be implemented. I'd like to hear from community first. 

Thanks,

Weiji Guo