> ...but at what point does Article 5 get invoked

Probably not as likely as you think.

First, these things intentionally fall short of clear "armed attacks" and are designed around plausible deniability.

Second, Europe/NATO are not looking for a fight. Russia is in a bad spot right now, but NATO is not in a great spot for a kinetic conflict with Russia either.

Lastly, I don't think NATO countries are eager to test America's willingness to defend Europe under the Trump administration because they already know the likely answer when they call for help.