@damieneskimo - I have developed my own set of Elgg REST API and its working fine with version 2.2.2
Here's the link: https://github.com/rohit1290/elgg_with_rest_api
For list of API visit: https://github.com/rohit1290/elgg_with_rest_api/blob/master/README.md
For more details on how to use the API is available at "APIs" folder > "API List.html" file in the repository.
Security issues should be reported to firstname.lastname@example.org!