I think the feature has been removed because TLE are very inaccurate and also because the discontinuity between TLEs can be very important. In other words, in a TLE serie for a same satellite, you can have TLEs with an accuracy of hundreds meters and some other with an accuracy of several kilometers (e.g. TLE propagated vs. "true" position). So, discontinuity isa major issue.
Something interesting could be to fit a TLE serie. For instance, using something close to what @markrutten developed. This code has been discussed in the following topic (stateToTLE() call from FiniteDifferencePropagatorConverter.convert() fails to converge (#859) · Issues · Orekit / Orekit · GitLab)
StateToTLE.java (17.9 KB)
Best regards,
Bryan