Choose the target style first—sentence case for a sentence, title case for a heading, lowercase for a normalized identifier—and apply it consistently. Then review proper names, acronyms, product brands, and technical terms that an automatic converter may mangle.
A case converter is useful for a bulk first pass, but compare a few representative rows before changing a large list. Unicode casing can behave differently across languages; i, I, and dotted or dotless variants are a good reason to test the language you actually use. Preserve the original when exact spelling matters.
The goal is readable consistency, not blind uniformity.
Akousa