I tried to update the translations for gnome-weather by using the POT file from Damned Lies, but the messages in the TypeScript source code were not reflected in the POT file.
It seems that the POT file included in the 48.0 tarball downloadable from Releases · GNOME / Weather · GitLab does not have this issue, so it might be that the xgettext used in Damned Lies does not support TypeScript. According to the GNU gettext release notes, support for TypeScript was added in version 0.25.