There is no documentation for the scripting and managed language bindings. You must use the C API docs, understand that mlt++ is simply a thin C++ wrapper over the C API, and then understand how the C++ API maps to your script language per SWIG. It is actually not as bad as it sounds. Basically, look at the included play script for your language, trace a MLT call to its C++ counterpart in mlt++, and then trace the C++ method to its corresponding C function. After a few times, you shouuld understand the pattern.
Nearly everything in MLT C API is available in the scripting language except for parameters on mlt_events. If you will need that - for example the frame object reference on consumer-frame-rendered event - then you will need to consult the SWIG documentation and modify the binding interface definition src/swig/mlt.i.