I know that Euro is the second most traded currency but it doesn't have the #1 spot because of the US Dollar (which is printed on top of piling debt by the way) since oil is priced in USD per barrel instead of quoting it in EUR per barrel (since the US has monopoly on oil).
Money printers for the USD are running constantly, going "BRRR" and have a high national debt. They're putting themselves further into that hole whilst printing more cash. What about the Euro? Is it even printed that often 24/7 or controlled to print a capped amount?
The only way to really Euro become superior is to incentivize it on a international scale (more than the US Dollar) on getting countries to accept & trust it more (but USD accounts for 60% of global commerce) so the Euro has A LOT of catching up to do on that.
Does the EU really have power or control over OPEC (Oil)? If they can grasp monopoly over the Gulf states by convincing them to price every barrel in Euros: would that strengthen the currency? The British Pound is the former global reserve currency before the US Dollar.
If European travelers stopped converting EUR to USD, only using EUR for international travel towards currency exchanges: would that increase the demand for it since US Dollar is literally the default for A LOT of countries (even "third world" ones) in terms of payment.
Arbitrary numbers regarding forex aren't an indicator: so what if 1€ is worth more than $1? It's more on PPP and trust, so with a stronger Euro traveling abroad (including the Americas): does that make it cheap for you to visit as you're able to buy more than they can?
Australian dollar is a weak currency for international travel I've heard, as the exchange rates are always lower than referencing from USD (like for example, A$1 = 0,60€ making it expensive). Like not all countries accept AUD at face value while USD is literally recognized everywhere.
Basically, they would have to pay more. Don't even talk about currency exchange with AUD, as you will get less than USD holders, for instance: A$100 = 60€ while $100 = 87,20€ (A$146), which is why refrain using Australian Dollar for international travel (just bring US Dollars instead).