The localedef utility, compiling a locale with all supported keys in the LC_TIME section, produces a 45-line LC_TIME file, which is rejected as invalid by 'locale', instead of the correct 58-line one.
Can you provide more information on this (localedef invocation, input/output files)?
Looking at this again, localedef(1) is supposed to work on posix-compatible data and we differ for LC_TIME having 2 additional specifiers (altmon and d_md_order). The resulting files are plain text and the format is visible in share/timedef/ files. Given the above, I'm going to close this as "not a bug". Please reopen if you don't agree.