Thanks, that’s exactly what I was looking for. Deeper down from there, I also found the information that:

1. Countries/languages were allowed to continue putting the € in front or behind, like where they put their currency sign before the euro was introduced.
2. Yes, for English, it was decided on before, because of the £ and $.
3. The English EU style guide says explicitly:

   The euro sign is followed by the amount without space: “a sum of €30”
   The same rule applies in Dutch, Irish and Maltese. In all other official EU languages the order is reversed; the amount is followed by a hard space and the euro sign: “une somme de 30 €”

Sources:

• 1 & 2: https://en.wikipedia.org/wiki/Euro_sign#Use
• 3: https://style-guide.europa.eu/en/content/-/isg/topic?identifier=7.3.3-rules-for-expressing-monetary-units