Contributions to FRUT are very welcomed and you can contribute even if you don't know anything about CMake.
You can simply convert your existing JUCE projects using Jucer2CMake
and build them
using CMake (see https://github.com/McMartin/FRUT#getting-started). Then create issues
(https://github.com/McMartin/FRUT/issues/new) to report any unwanted differences with how
your projects are usually built when using Projucer.
Several existing issues are labeled "missing feature" and are only waiting for you to comment on them to express your interest for these features. If FRUT is missing another feature that you need and there is no issue for that feature, feel free to create one!
Some of the issues are also labeled "help wanted" because they concern features that require acquiring third-party SDKs and tools. We need developers who are familiar with these SDKs and tools to build and test theirs JUCE projects while we are adding these features to FRUT.