${LOCALBASE} in LIB_DEPENDS in doesn't work?

I guess this falls under style preference but for consistency and logical reasons I'd place these variables before CONFIGURE_ARGS

Should be formatted so it's readable?

Do you mean such line as below?

LIB_DEPENDD= ${LOCALBASE}/lib/libffi.so:devel/libffi

If so, unfortunately it doesn't.

Order of variables in Makefile is sorted with portclippy.

It is formatted with portfmt.

I would argue that some are logically incorrect but it is what it is :-)

It's much harder to read (follow) than

--exclude ${DISTNAME}/bin/gem \
--exclude ${DISTNAME}/ext/win32* \
--exclude ${DISTNAME}/lib/bundler* \

....and so on?