Hi Wilfred,
Thanks for the detailed update.
The sandbox instance is still running on the 18.03 release version of both Fineract and the front-end.
and Fineract 1.5 is compatible with the Mifos release version 21.07 or the latest Develop branch.
Backward Compatibility sounds good technically but will be challenging on the functional/feature side and also at branch maintenance.
For example: Fineract might have new features developed, but backward Compatible Mifos may not have the screens to use that and vise-verse.
Mifos /Fineract follows the approach of adding fixes/features on the develop branch always and does the tag cut-off during the release process.
Hence I feel we should always go with the latest of both code bases or the correct release version codebases to get the full benefit of the features/changes made.
Latest releases
Having said my opinion, I will leave it open to the community around this discussion, we could always go with what is best for the users.