After discussion with some of the docs team, a new Style guideline has been added:
. 9. Sponge is the project Title and preferably should NOT be translated.
. Some languages may wish to use a phonetic translation as well.
Basically, Sponge is the product name - a proper noun. It's like a corporate brand, and should not be translated unless there is no reasonable alternative. For some alphabets, a phonetic translation may be helpful.
The preferred option is to use the word "Sponge" in the English alphabet, the same as it appears in the code. For good or ill, English is embedded in Sponge, Java, and the Internet at large.
As always, constructive discussion is welcome.