No, just setting memory variable $006B to $03, as you mentioned, is enough. But thanks for the offer.
Having investigated the code a little further, it seems to me that the PRG bank order is mixed up, but only slightly. There already is a Waixing Mapper number for that --- Mapper 249 will mix up the PRG banks if register $5000 has bit 1 (value $02) set, which Ling Jie Hu Fa indeed does right at the beginning. Unfortunately, the scrambling pattern seems to be entirely different from the existing Mapper 249 games ...
- Duo Bao Xiao Ying Hao - Guang Ming yu An Hei Chuan Shuo (Ch)
- Myth Struggle (Ch)
- Shui Hu Zhuan (Ch)
... so one would have to find out what the correct pattern is. Those three Mapper 249 games freeze right away when run as Mapper 4 or 176, so to account for the fact that Ling Jie Fu Ha seems to mostly run well, the alternative pattern may invole changing only a single bit. Other games that write $02 to $5000, yet seem to run normally at first, but may crash at a later point for the same reason:
- Golden Axe
- M&M Heroes (serial 980100295)
- Ye Ming Jue
Has anyone played these games to tell me whether they crash at some later point?
There is an alternative version of M&M Heroes with serial 980584 that does not write $02 to $5000, so maybe comparing the two versions can lead to some insights.