Might as well mention “Sancta Marīa” in Latin, for example from the Christian Hail Mary[1], a recorded Latin version[2], written Latin next to English and Spanish[3] and of course translated into thousands of languages[4] although unfortunately mostly written using /A-Z/i; I am an atheist interested in languages.

[1] https://en.m.wikipedia.org/wiki/Hail_Mary

[2] https://glaemscrafu.jrrvf.com/english/avemaria.html

[3] https://hymnary.org/text/hail_mary_full_of_grace_the_lord_is...

[4] http://www.marysrosaries.com/Rosary_prayers_in_different_lan...

In my mind, the Latin form of Mary is Mariam, because that's what my Latin teacher taught me. (He also commented that, unlike Greek names, Hebrew names never inflected in Latin, so that it would be "Mariam" regardless of what case the name should appear in.)

But it makes sense that Church Latin would be different.