There is an abundance of other corroborating evidence of high Jewish intellect beyond just IQ tests, including earnings and educational attainment, which are basically impossible to explain solely through nepotism

Guess you haven't read Ron Unz the myth of American meritocracy, which explains it quite well. Can also think of numerous other articles on the occidental observer that do a pretty good job of it, as well as other places that have mostly been scrubbed off the internet and memory holed. It's really not hard to explain at all, but it's getting harder to explain it away as Jews are just so damn smart when all this supposed evidence keeps turning up to be borderline fraudulent and no study would ever be allowed that Jews didnt find palatable due to their enormous wealth, aggressive lobbying capabilities and academic clout.

I think there is evidence Ashkenazi Jews on average might score better on IQ tests and do better at SOME tasks which are heavily represented in IQ tests, and some circumstantial evidence they are worse at some tasks that aren't heavily weighted on IQ tests. How much of this is environmental and how much genetic its hard to say because of Jews extreme wealth, privilege, and a culture that places heavy emphasis on literacy and scholastic achievement(to their credit, im not knocking em for it). In the early 20th century when Jewish immigrants scored below average on tests poverty was largely blamed, so you cant have it both ways.

If you’re a race-realist, denying this and other evidence that Ashkenazim have a higher IQ basically puts you in a more difficult position, because now you need to argue that these things that indicate higher intelligence are true among whites and other groups

I don't see why this would be? The two are not mutually exclusive. In the case of say comparing west Africans to Northern Europeans, you are talking about up to 200,000 years of divergent evolution in vastly different environments, with one group deriving up to 20% of their DNA from an as yet unidentified pre human ancestor. You are talking about periods in history where whole groups of people died out due to evolutionary disadvantages and entire groups survived due to likely evolutionary adaptations, over and over again, for tens of thousands of years. With jews you are claiming they went from the low 90s ave middle eastern IQ to 112 in a little over a thousand years, when such harsh evolutionary survival of the fittest pressures were non existent. You also seem to be claiming they are across the board "smarter", despite filling niche roles in preexisting societies they didnt have to build or sustain. Seems to me at best such an environment might give rise to some specific cognitive skills while others atrophied, but either way in such a short amount of time I wouldn't expect to see much of an impact either way.