From Japanese mahjong wiki
The "ambiguity" section needs to be rewritten in a way, such that the case describes "karaten" rather than "keishiki tenpai", as the latter is not applicable. KyuuAA (Talk:キュウ) 14:03, 23 May 2019 (UTC)
I had to take this out. But here it is:
Tenhou staff have confirmed that there was a decision to simplify interpreting if a hand was tenpai due to programming constraints.