In new Dominion terminology, "for" and "to" mean that you must have actually successfully done the thing to get the bonus. Pretty simple.
Yes, sure. My complaint isn't that new Dominion terminology is unclear when understood as Dominion terminology, it's that it's unclear when read as ordinary English; and given that old Dominion terminology didn't require that distinction, the old terminology was better in terms of clarity. New dominion terminology is better in terms of brevity.
If you prefer brevity to clarity, hey, that's fine by me. Just don't expect me to give you a favourable code review.
I think it's fine when read as ordinary English, and the playtesters as a whole must have agreed. If enough people have a problem understanding a wording, it generally gets changed.
I concede that "if you do/did" may have been better on Mill. Maybe part of that is on me; the font size I was using when mocking up these cards—larger than the first edition font size—allowed "You may discard 2 cards, for +$2" to fit on a single line. But when Matthias actually settled on a new font size for Empires and second editions, it was even larger. So, being that the new Mill uses two lines for that text anyway, sure maybe "if you did" was the better call there.
I'm still not convinced it's actually confusing to new players that aren't trying to be pedantic.