The first machine I tried was an ARM (aarch64) and didn't work. This is because, I believe, Rosetta does not craft their work units to process correctly in ARM.
Yeah, I can add a couple additional things need done to host an ARM project on boinc. Its not a limitation of Boinc or the Rosetta Project.
Basically, the Build of Rosetta produces a long compatibility string, something such as "Linux 64 - ARM - Kaeplin" and when the Rosetta developer finds that string, they have to ask Rosetta web admin to add it as a project type (So then Rosetta supports Windows, Mac, Linux, Arm Kaeplin). After that nothing works yet. Then they have to have config manager build a Kaeplin build. Then Network manager configure the outputs to go in the Kaeplin directory. Then enable Boinc Rosetta to serve those workunits. Then script a program to Create work units for Kaeplin.
So its everything from a custom build for that proc to enabling that proc for the project. They probably only support one Arm build at this time, whatever one is in the google play store that works on the galaxy s7.
You can make posts in the Rosetta forums asking them to support more Arm flavors. You can get the string from the task scheduler error, where it says Project has no tasks available for "Arm xxxxxx".