I made a Proposal some time ago how I think the Feitoria could be used in the general civ design as a tool in castle age and at the same time balance it for the lategame.:
Otherwise I am actually torn about buffing portuguese more than that. The civ can be quite strong in some closed and naval maps already. I thik that kind of tool that helps on more “agressive” maps in castle age as a reduced investment in eco that pays of earlier but less in the long run than standard TC additions could give the civ the right “tweak” to be more viable on open maps.
The thing is I now tried to figure out what exactly goes “wrong” with this civ and still couldn’t really figure out. From the sheer bonusse it has it should perform way better than it actually does. It’s hard to understand and therefore also hard to say what causes the civ to “underperform” in that way it does.