It seems to me that fresh pulls of gnumeric into existing installs require a 'make clean' before the build since sometime after 2022-09-21, else t2001-func-help.pl fails with:
't2001-func-help.pl: Checking function help text sanity.
Differences between actual and expected on line 5:
Actual : E Cannot load plugin loader.
Expected: Result = 0
Fail.'