Evolution of Pokémon Bank Events (in terms of WC Title localization)

[theSLAYER]

When Bank event titles was just English

Mewnium Z
During the release of Mewnium Z, it appears that players could already choose Pokébank's operating language (source). Additionally, since X&Y, players could choose which language to play the game in. (source)

However all Mewnium Z cards only came in English, regardless of Bank's and the game's language.
Example 1: Redeemed on SPA Bank and SPA Save (contribution) (images for that contribution)
Example 2: Redeemed on CHS Bank and ENG save (contribution)

When Bank event titles were now localized

Alolan HA Starters
During the release of the Alolan HA Starters, it became known that the wonder cards had their titles localized. (example 1)(example 2)(example 3)

Back then, it was said that deleting your save and starting anew was enough (source),
but in hindsight I am not sure if this referred to Bank or the Game.
 

Passimian/Oranguru HA
I have received information that states that what controls the localization, was Bank's language, not save's language. Since my gift was already redeemed, I did a test with Battle Points instead.

CHS Bank language -> ITA save language

As you can see, the wonder card title received was in CHS. This pretty much confirms the information that localization follows Bank's language. It is not known at this moment whether the Alolan HA Starters used the same method as this or different method.