Translate master should be backwards compatible but a commit on the master branch is (https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Translate/+/730189) dependant on a commit only in VE master (https://gerrit.wikimedia.org/r/c/mediawiki/extensions/VisualEditor/+/725297).
VE support is based on release branches so the VE changes need to be on all Translate Supported release branches.