(note: I'm just someone taking a look to see what is blocking the unicode-data "transition", i'm not a maintainer of this package or a member of the release team).
unicode-data 12.0.0 is now in unstable/testing (Buster). gucharmap FTBFS with this;
It seems upstream have updated gucharmap for unicode 12.0. It appears that upstream releases of gucharmap are versioned based on the version of unicode they support, with an extra element added to the end for updates to gucharmap only. So the large increase in gucharmap upsteam version number does not indicate massive changes to the software. The total changes between the versions are quite voluminous, but they appear to be mostly translation and documentation updates. Filtering those out ( I used git clone "git clone https://gitlab.gnome.org/GNOME/gucharmap/"; followed by "git diff 11.0.3..12.0.1 | filterdiff -p1 -x'po/*' -x'help/*' --clean" ) seems to leave a quite reasonable remaining diff. However debian sid has now moved on from unicode 12.0 to unicode 12.1, there is an upstream bug report for 12.1 support, but so far there doesn't seem to be any publically visible activity on it. https://gitlab.gnome.org/GNOME/gucharmap/issues/17
