CLDR 32 Survey Tool input changed a few of the German am/pm strings from German abbreviations for "before noon" and "afternoon" to English AM/PM. This was done inconsistently, and was controversial, so for stability it was reverted in 32.0.1 (), and this follow-up ticket is for reconsidering the issue.
Written German uses 24-hour time.
Spoken German uses 12-hour time with multiple day periods.
CLDR does always provide am/pm strings even if they are not commonly used in the language, so that software that explicitly selects 12h am/pm time format anyway can use understandable strings.
The long-standing German am/pm strings "vorm." and "nachm." were chosen as approximations: They are understandable, but they sound odd when they are not a good match for the time (e.g., 10 at night). The later additions of narrow "vm." and "nm." strings are more obscure.
Many German speakers know English and are likely to recognize AM/PM, but they would recognize them as Englishisms in a German UI.
On one hand, we can provide native strings as much as possible, even for formatting choices that are uncommon in the language, resulting in strings that are not "right" in all uses.
On the other hand, the argument has been made that users who //choose// a German UI with 12-hour am/pm format are not native German speakers and are likely to be more satisfied with English AM/PM strings.
(Has this argument of choosing other-language strings for uncommon formats been used before for CLDR?)