Hi Hans,
That works for me, I patch the core-con.lua with your implementation, update the local cache by running `mtxrun --script cache --make`, context my document and get the same "as-is" result as before, I think that would be a valuable idea to have an extra as-is function for potential number conversions.
And I just realize, for Chinese date, only year section follows the as-is pattern, for month or day, December should be represented as 十二月 instead of 一二, twenty-sixth is 二十六日 instead of 二六, we might need to consider to narrow down the name to be year could be more precise and meaningful.