GSE doesn’t do anything. It simply takes what you enter and passes that to WoW and says to WoW’s macro engine “please do this thing my player thought up.”
With translating macros are only evaluated in the clients local language. Macros with English spell names running on a German client are completely ignored by WoW. There is also no universal way to translate a macro so it works on every client. I have done what is possible with spell abilities but with conditions it is next to impossible to determine that a spell is in there.
To translate spell names in conditions the macro author would need to create a GSE variable and then from that variables function call GetSpellInfo for the WoW spellid of the spell the were using and return the local name for that spell. This is the only way however that takes effort on the authors part which few if any are either willing to do or have the mental fore thought to think that this is something they might need to do for international users. This is a capability that has only just been added to GSE but requires people to really think about what they are doing.