Somewhere in your analysis there's a flaw. In other words, you are wrong slimboyfat
What I see in Hispanic congregations is that people who get baptized are mostly born-ins and few immigrants who feel lonely, have limited education (9th or lower) and/or have no access or interest in the internet.
It's a new world, it's not what it used to be even 15 years ago when congregations had to split every few years to accomodate newcomers. English congregation actually are merging because they are losing "parishoners" and therefore there are too many empty seats.