At Kassel University we are working on a solution for bidirectional transformations based on event sourcing for about a year, now. It turned out, that the TTC 2020 migration case is a special case of a bidirectional transformation and that our approach provides a reasonable solution for it.
Cite
@article{arxiv.2012.05231,
title = {The Fulib Solution to the TTC 2020 Migration Case},
author = {Sebastian Copei and Albert Zündorf},
journal= {arXiv preprint arXiv:2012.05231},
year = {2020}
}