This module has been developed for more than a decade and seen different maintainers over the years. The codebase is indeed showing these, with different capitalization and indentation styles, among other things.
However, among more than a dozen or so of INI modules in CPAN, ironically there seems to be few other choices if you go beyond the most basic feature set. Some INI modules can only simplistically rewrite/dump the whole INI structure and thus lose comments/orders, while others can't even write INI files.
Config::IniFiles by far offers the most options and features, like dealing with line continuation, case sensitivity, default section, multiline/array, deltas, etc. So for now, despite all of its quirks, this module is still hard to beat.
There's another nice little INI module that can do read/set/delete/unset (instead of just read/dump): Prima::IniFile, but it is included in a totally unrelated distribution.
documentation is imprecise, and does not take into account edge cases. api is designed to return undef, even in list context, rather than (). test suite is far from complete. bugs exist when using IO::File objects, and they're completely untested.