To be clear it's not that good either, but it's still not that bad. Honestly, none of the Lost Tomb stories have been that great. I'm watching them in order and so far none of them make me want to recommend them. Chronologically, I couldn't tell if this was before or after Mystic Nine. They didn't mention any years that I can remember. Perhaps that was on purpose.
As in the others the action here is good. The tomb is nicely done albeit small and they're not in the tomb for very long.

While Mystic Nine wants to drill in how horrible the Japanese were (like the Chinese are any better ..ok I'll put my sociopolitical pov away), this side story bashes you over the head with it. Quite frankly, it's annoying. The writing is lacklustre. The acting is just ok. No one is winning any prizes here. The production could be better, but I don't think this was a theatrical release, at least I hope not. I will say I liked Er Ye much better here since he wasn't screaming Ya Tou every 3 minutes.

The acting...wait was there acting? Like I said above no one is winning any awards although I did enjoy the performance of Mo Yuan Di, who is an actual Chinese opera theatre actor. I found the voices of the 2 main Japanese characters annoying. It's rather hard to judge acting when most if not the entire movie has been dubbed and this one was obviously dubbed probably from Canto to Mando. (Most English subs are done on the Mandarin dubs.) Anyway, many times the voices and mouths weren't synced.

Generally speaking, I don't do re-watches of dramas, but movies I do. However, I will not be rewatching this one. I have no interest in seeing it again. The music suited the movie.

Overall, it's not bad to watch on a Saturday afternoon movie binge, but don't make this any kind of highlight. If you do, you will sour.