I don’t know if I would be happy, probably more excited. Although I would be suspicious. I’m willing to wager any first contact with aliens will be a false flag operation.
I also doubt that any intelligent alien life exists at all, especially one that has mastered interstellar space travel. The (man-made) idea that little green men flying around in spaceships is just about as ludicrous to me as assuming humanity evolved from amoebas by chance without any anchoring of a divinity in our world of perfect design. But we are an arrogant species thinking we have discovered the answers to life, but have yet to colonize a planet or leave the galaxy and have found nothing but rock and gas outside of our orbit.
You may think that our “quaint religious beliefs” may be challenged, but it doesn’t contradict anything from a Catholic perspective. Science and religion are only at odds if you have a closed-minded binary way of thinking while searching for a flawed concept of God through one particular lens. If you find this to be inaccurate, speak to the priests who have degrees in astrophysics who run the Vatican observatory.