Your information is correct for that benchmark, it's a general performance indicator that is definitely better than just guessing some round number based on nothing but power draw or expectations, however it doesn't give you how that CPU performs in a game, it should be somewhere along those lines, but since different benchmarks can find different bottlenecks, there is no great way to do it.
However, A78 should have a much higher performance per clock over A76, and I'd suggest over 2GHz on 5nm is likely going to be a thing, since A78 is designed for both 7nm and 5nm, and I can't imagine that it will be designed to run at ultra low clocks, where something like a successor to A55 would fill in better.
Just to give an idea of expected performance gain of A78, A77 is 20% faster than A76 in some benchmarks, we can see from the first picture that A78 has a similar jump in performance expected, so if you look at that 2.0GHz A76 single core test, and compare it to the expected results for A78, you'll find that a 2GHz A78 core would get very close to the ryzen 3700 3.6GHz single core benchmark of 1254, somewhere over 1200. I'd expect Ryzen 4000 series in PS5, so whatever IPC increases found in the new Ryzen chip will be there, but PS5 is also a 3.5GHz chip, and I expect over 2GHz for A78 in a Switch.
This is again not an ideal comparison, and 8 cores @ 2GHz on 5nm is going to draw between 2 and 3 watts probably, but until A78 comes to market, we can't say that for sure, an A77 powered Snapdragon 865 with 4 A77 cores over 2.4GHz (1 over 2.8GHz) and 4 A55 cores + Adreno 650 (a 1.25TFLOPs FP32 GPU) draws only 5 watts on 7nm.
I actually think one thing Nintendo might do is clock 2 A78 cores higher as well, something like 2.4GHz on 2 cores and 2GHz on the other 6, if they use A55 cores, I'd suspect that the OS cores might be clocked differently than the ones reserved for devs, but considering 8 threads is probably enough for next generation, they might not need it.
I think the SoC power budget will go up by virtue of the screen being much more energy efficient in a Switch successor, much like the screen in the new models of Switch, the launch model saw a 7.1 watt to 9 watt power draw based on how bright you had the screen, expect something better than that, leaving room for Nintendo to increase the SoC budget from ~5 watts on Switch to ~6.5 watts on the successor.