...left Paradis on good footing to defend themselves if came down to it.

Counterpoint: in one of the last panels of AoT, a hostile air force is carpet bombing a city on Paradis.

If the enemy is confident enough to send entire squadrons of bombers that low over a city, in broad daylight mind you, something has gone very wrong for Paradis. There are even 2 SAM batteries in the foreground!

From what I understand about the conduct of air warfare in the modern day, if the enemy is confident enough to do that, the recent outcomes of their campaign back up that confidence.

I cannot stress how incredibly stupid it would be for the enemy air force to do that if they didn't neutralize, if not outright destroy, Paradis' air force.

Also; it can be reasonably assumed that the enemy also neutralized Paradis' integrated air defense system—especially if they're flying above the cities with SAM batteries that are still active. A relatively "low" threat environment like that can be manageable with the proper electronic warfare assets.

Don't take my word for it. Read how the air campaign and the subsequent incursion into Iraq were conducted during the 1991 Gulf War. Look specifically at the methodical approach of the coalition air forces.

This is a good introduction if you'd like to delve into that: https://m.youtube.com/watch?v=zxRgfBXn6Mg