Version 5.2 is now out with some nice contributions from external contributors. The first one is the implementation of tablature features newly introduced in MEI 5.1 as part of the E-Laute project.
The other contribution is the rendering of score annotations encoded with control events annot
elements. This was implemented as part of a follow-up project of the Beethoven in the House project at the Oxford e-Research Centre.
The additional improvements brought in version 5.2 include better support for repetitions encoded with expansion
elements, more flexible staff ordering, and support for SMuFL encoding for note heads.