With the boofcv-javafx issue, is that a transitive dependency or do you explicitly include it? Work was started on that and stopped. Might be removed eventually. There's no need to include it unless you want to help start that project up again.
The code to do a 3-view calibration and reconstruction is certainly there. There isn't a nice tool yet (one is planned) for calibrating an N-camera system with synchronized frames. The semi-manual way to do it would be to use the existing tools to calibrate each camera individually, then use an ECoCheck marker and use that to estimate the extrinsics between the cameras. For reconstruction from three calibrated views, the easiest way might be to modify the uncalibrated example by removing all the code where it does self calibration. Then feeding in known calibration values you found previously.
FYI there is an active project right now where a batch multi-camera visual SLAM algorithm is being implemented. While overkill, that might make these tasks easier.