Setup Failure Codes/GNU gettext support
The page identifies a minor configuration problem. Some functionality may be impacted but most parts of DAViCal should work fine.
The GNU gettext support is used for producing translated output.
If you don't have gettext support, DAViCal might still work but all output will only be in English. We also don't *test* that this works, so it might just be plain broken, so we do recommend installing GNU gettext unless you're trying to run DAViCal on an OpenWRT router or something and memory constraints are really tight. And you're willing to track down, file and justify any bugs.