Looks like fake science - I can't see anything useful that's specific to ASD at all:
...
Additionally, there is evidence to suggest that bilingualism can be beneficial to both autistic and non-autistic children. Indeed, a growing body of research highlights the potential benefits of bilingualism for non-autistic children in terms of sociocultural factors, including family bonds.
...
While comparatively, there is limited research addressing the effects of bilingualism for autistic people, in terms of cognitive skills, the literature that does exist suggests bilingual exposure does not lead to poorer development.
.....
Howard et al. (2019) reported that bilingual children living in multilingual environments are more positive about bilingualism than their peers in monolingual settings, especially regarding social and communication opportunities linked with bilingualism.
The only claims that seem reasonable are that there's a cultural benefit if you can find the time to teach (all) children their "second" parents language. This is consistent with my own experience (EU country, local language was mother's, English taught in schools), but this is the easiest way by far to learn the father's language.
If it's a third language (neither mother's language nor the most common second language taught in schools) it's possible, but it's a
lot of work.
IMO the authors need to make a much stronger case for this being worth the effort for all children, and then start looking at ASD.
BTW
It was common for culturally Chinese kids when/where I was a kid to learn to speak, read, and write "Chinese" (probably actually Cantonese there, but I don't know for sure).
Anyway the kids complained about it while we were at school (because it's a major effort), but were happy about it later.
Which suggests there is a lot of data available. yet that article is very light on data or
relevant unqualified claims.
The issue for us isn't if it's possible, but the practicality of spending this much effort on language for a "non-HFA" ASD as an alternative to other areas of study/training. I'm wondering if it's a cynical attempt to get ASD-linked research funding for someone's favorite activity.
As a kid I'd have preferred learning indirect speech and intonation in my local language; local body language, and social skills. An extra language isn't a bad thing at all, but unlike those three skills, lacking a second language while young wasn't the source of any significant problems in my life,