I just saw this somewhere on Youtube or something and went through all their papers.
The concept looks decent. Apex seals in the housing instead of the rotor should make them more reliable I'm guessing.
Compression ratio can be pretty much as high as you want, that's good. Could set it at 18:1 expansion, 12:1 effective compression for similar VE to a Mazda Skyactiv-G.
Increased dwell actually isn't good for low speed given the surface area to volume ratio is still poor, but you can just run the engine at high speed only as a generator or something.
Since you have most of the combustion chamber in a quench/squish zone and a tiny pocket to ignite most of the fuel, combustion speed is not a problem. Then again, combustion speed is less important if you have a really big expansion ratio.
Now the bad:
XMv3 indicates 18% peak efficiency, 5 bar IMEP, 4 bar BMEP without Atkinson cycle intake "timing". That is BAD. A similar sized Wankel from AIE gets almost 7 bar BMEP:
https://www.aieuk.com/40s-5bhp-wankel-rotary-engine/ The sealing must not be working, or something. A dyno chart would make it easier to figure out what's wrong.
The rotor has a similar problem to the Wankel: one side has the exhaust constantly going through it, the other side goes through intake/compression/expansion. There's definitely going to be a big temperature difference, which might contribute to poor sealing. Since you can't liquid cool the rotor, this is probably a big problem, since even if you're using inconel, the exhaust side would expand by several thousandths, that's going to create some bad vibration for the apex seals. A carbon ceramic rotor with dry lubricant ceramic seals might work, at very high expense. Another idea is to use intake air to cool the rotor, but that reduces power density and WOT efficiency.
It looks like the rotor air cooling blows out the exhaust? That can't work for any emissions controlled engine, can't be mixing fresh air into the exhaust.
I'd like to see what happens with a bigger sized demonstrator if they ever come out with one. The bigger size alone would make sealing, cooling loss, and pumping loss less of a problem.