Does that one not work for MBL as well? I suppose you could enable UBL and use a manual probe option in Marlin. Wonder if the EEPROM Settings editor would allow you to adjust that.
I'd ask the author of OctoPrint-UBLMeshEdit (open an issue on the project) for help. I think the gcode commands are similar if not identical. If the author doesn't want to add MBL support, they may be willing to assist you with a fork of the project.
Actually, I've been pretty clear that it does not support MBL. ABL can work with some limited functionality, but MBL is too quirky and I don't want to try to support every edge/fringe case.
edit: There are already at least 3 issues for this. Please don't encourage more!
If you can't or just won't take a look at using UBL instead, feel free to take a look at the first iteration of the plugin, which was for MBL only:GitHub - The-EG/OctoPrint-ManualMeshEditor
Be aware, it was unfinished and it's completely unsupported and I will not be updating it. I decided part way through developing it that using UBL was a better approach than trying to code around all the MBL oddities.