Well, to begin with, the Swedish government seems to have known for a rather long while that Nordea has been doing quite a lot of other shady shit abroad, and still stuck with them... From your own WP cite, a bit further down: https://en.wikipedia.org/wiki/Nordea#Scandals .

Not that the Swedish government is much of a guarantor against sending sensitive data abroad in the first place: They were quite OK with the Swedish Transport Agency letting a contractor (Oh look, IBM again!) hand over data, including higly secret (protected identities, military vehicle registry, security van routes and timetables) to sub-contractors abroad with no Swedish security clearances: https://simple.wikipedia.org/wiki/Swedish_Transport_Agency%2... (very cursory article; much more in the Swedish-language version). So them trusting Nordea... Isn't much of a recommendation for Nordea either.

If you're extremely skeptical that the Swedish government would be OK with handing over the keys to their economic kingdom to cheap digital labor abroad so a company might save some money, then you need to re-evaluate your mental model, because that is definitely happening in reality. They may impose some legal limitations - the exact same limitations as towards any other bank - but they generally act as a normal minority shareholder, demanding the company to be cost-efficient and maximizing profit even if it means outsourcing and offshoring.

You think core banking process like transfers/ trading is some kinda crown jewel. It may be in terms of messaging but most of core IT part is just a cost center.

Customer data and all need to be in their own secure data centers for legal reasons but all the processes can be designed, developed and executed from anywhere at lower cost.