I don't have sufficient knowledge about construction details and combat report evaluations to form a substantial opinion. I would have expected the 29 to be somewhat stronger than it is know, but that's just kinda layman thinking 
I don't think anyone does, mainly because there is comparatively little information of this sort available for B-29s.
In the ETO there were lots and lots of B17s and B24s over a span of years. In the PAC there were just a few hundred B29s for less than one year.
In the ETO bomber crews bailed out over land, generally, and those who survived could tell tales. In the PAC B29 crews generally went down in the vast expanse of the Pacific and were lost.
I know that I was very surprised when I read about how the MiGs clobbered the B-29s in Korea. Somehow I had just expected that the B-29 would be at least as tough as the B-17, and that no second generation Bolshevik jet fighter was going to do much harm zinging by at those speeds.
It just might be that HTC has correctly modeled the B29, and we were expecting something else based on information that didn't apply to B29s.
- oldman