Most of these "project-but-without-" forks tend to be abandoned rather quickly unfortunately. Maintaining compatibility with a large codebase that is not yours is not the fun part of software development.
I would say clbre and arcalibre are already abandoned, looking at the activity on these repos (none in clbre, and issues/PRs piling up in arcalibre). If you can envision yourself still dedicating your time to this endeavor 5 years from now, you might as well move forward with your own thing.