Problems, yes. Catastrophes, no. It's not clear that they "needed" full backup capacity.
Not necessarily. If connectivity is broad and the network graph is decentralized, rerouting should cover some of the backup.
For example, if Luxembourg goes to war with Belgium, and Belgium shuts down the lines to Luxembourg, then they can reroute via Germany or France (provided they have lines there, obv). But if Spain gets beef with France, and France cuts the lines, they cannot easily reroute. So Spain would need more backup and more independence (and prolly cables to Italy and Africa?). Point being:
Most renewable energy investments have decent, easy to calculate returns on investment. That's why this stuff is so popular with investors. And that's also why I don't think current policy changes in the US matter long term. It just slightly increases the time to a return on investment. But you still get a return. So, companies will continue to look at batteries, solar, and indeed cables with or without government support. And even a little bit of tariffs (aka. taxes) won't stop that.
Even the EU with it's very tight integration between member states is seeing a lot of pressure to tear itself apart again from the inside, despite the very real costs thĺis would bring.