Here is a international journal I haven’t seen before on biligualism- I am not a cognitive psychologist so some of the term are a bit unfamiliar.

https://www.cambridge.org/core/journals/bilingualism-language-and-cognition/open-access

Reminds me of the scientific studies of reading which  publishes a lot around L1 L2 and dyslexia.

https://www.tandfonline.com/journals/hssr20

MDB