Instrument descriptions are already provided with the respective instrument names as extracted comments visible to the translators in Weblate above the source string.

This should be generalized for all the descriptions (artist type, relationship type...)

Note that adding/modifying extracted comments (in contrast with context keys)  doesn't discard the existing translations, so this change is very soft for translators.

See https://www.gnu.org/software/gettext/manual/html_node/PO-Files.html for more details about "extracted comments" in PO translation files.