I think so.
Al Smith's electability problem wasn't just that he was Catholic.
He was also Irish and Italian (people forget the Italian part!), at a time when negative stereotypes about both were prevalent.
He was also a native of New York City and proud of it, at a time when New York and Eastern cities in general were viewed negatively by the heartland and rural voters.
A Catholic to Protestant convert from, say, Illinois, wouldn't have had the baggage that Smith carried.
I mean, the ONLY Catholics at this time were immigrants ... so the bolded is only relevant if you think a German Catholic would have had an easier campaign than Smith. And I am skeptical of that.
That's not necessarily true - there were a decent number of Maryland and Louisiana Catholics whose families where well-established in the US by 1928. If, say, some Catholic Governor of Maryland ran in 1928, their Catholicism would be a disadvantage but not to the degree of Al Smith's.