Early L1 development concerns aside, learning cursive was a pretty good ROI for me given how little time it took as a seven year-old, and how much time cursive has saved me over the years since.
Related research:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7399101/
The second study compares handwriting vs tracing vs typing, again no cursive vs print.
The third study compares drawing vs typing, it doesn't address handwriting.
Also all of them are using proxy measures like brain activity and not recall of the studied material.
I could actually accept the more laborious and slower process of handwriting may slow kids down and therefore spend more time thinking about a subject as a hypothesis, but that's not what was tested here. Such a hypothesis would however favour print handwriting more than the theoretically faster cursive.
The students who only printed lagged on every metric: https://journals.library.ualberta.ca/langandlit/index.php/la...
Does the paper have any relevance to whether teaching cursive helps (causes) learning more generally?
Language is best when it uses as little processing as possible. Its meant to be a medium, not a mental task in its own right.
So taking your research claims at face value, that's not actually evidence that cursive is good. In fact, its the opposite.