"English (Traditional) vs English (Simplified)"

en_US would actually be closer to English (Traditional) than en_UK, if linguists are to believe.

EUs English guidelines emphasized en_UK because that used to be the main audience to whom texts should be unambiguous. That requirement is no longer there, so en_EU (which defacto exists, although it has many variations) might now officially move closer to en_US, since that is what most cultural exposure is to for those to whom English is not a first language (i.e. almost everyone in the EU).

I therefore propose a half EU/half US flag pictogram to refer to English from now on.

Yeah just forget about the Australians, Irish, South Africans, ...