I heard a Protestant pastor once refer to these types of people as “spiritually homeless”. They hop from spiritual soup kitchen to spiritual soup kitchen.
When God has a banquet waiting for them in the Catholic Church.
Our church is really good at capturing these poor wanderers - I should know, I was one!
In the narthex we have a guest book, and little grab-bags for guests to take home. It has the phone numbers of just about everybody, a schedule, a welcome letter, a wood cross, and a book on the next steps to take.
We have greeters that know everybody, and when someone new pops in, we welcome them and give them a place to sit in the pews next to an older member of the church. When communion time comes, the older member will sit with them so they don’t feel awkward not receiving.
When service ends, our pastor waits in the narthex to greet everybody who exits - he knows the membership by name (When he distributes the body of Christ, he does with each members name “Ben, body of christ broken for you.”) He’ll know who is a guest, and will give them a bit more attention and welcome them.
We have a committee that will follow up with our guests and encourage them. About a third of them enter our training, and about half of those will become members. In all about 1/8 of the people that wander into our church will become active members. All of them will at least have a better appreciation and a larger appetite for God’s love.
I say all of this not to brag, but in the hope that someone good Catholic reading this will take away some ideas and be able to grab some of those “church hoppers” and being them to Christ.