This is no crowdin.net translation issue, since the name in crowddin.net is "translated" as "Wither"
But in C:\Users\user\AppData\Roaming\.minecraft\assets\lang\de_DE.lang
entity.WitherBoss.name=Withern
MC-14795
Wither is still named "Withern" in German
Resolved
Fixed
4
kumasasa
(Unassigned)
Confirmed
CustomName, translation, wither
Minecraft 1.5.1, Minecraft 1.5.2, Snapshot 13w17a, Snapshot 13w18c, Snapshot 13w19a, ..., Snapshot 13w24b, Snapshot 13w25a, Snapshot 13w25b, Snapshot 13w25c, Snapshot 13w26a
Minecraft 1.6
Retrieved
Confirmed.