First thing's first: Check your humidity. Second: check that they used full spread glue with a wide plank install (5" or more = wide plank). Nailing alone is not enough for wide plank.

But the first thing you can do: check your humidity. Winter is a dry season and without constant, consistent humidity control wide planks do WEIRD things...which may not settle down for many many many years.

Google searching images will bring up some decent pictures: https://www.google.com/search?q=wood+floor+decorative+face+nail&biw=1280&bih=932&source=lnms&tbm=isch&sa=X&ved=0ahUKEwit4czu9uLRAhWLqlQKHXWVDrEQ_AUIBygC

It's odd that Pine would cup with an oil finish so I would recommend a couple things before taking any drastic steps.

Test the moisture in the top of the Pine, the bottom of the Pine and in the subfloor. If there's a huge discrepancy, determine whether steps can be taken to alleviate it. If there's a small discrepancy, consider waiting through a full year of seasonal changes to see if the issue works itself out.

Consider that drilling holes near the ends of boards and installing nails or screws and plugs, may have negative consequences. I'd be concerned about splitting. Will the cupping be pulled down with fasteners? If you drill and bore for a plug, the portion of Pine pulled down by a screw will be rather thin. Would it pull down the thin portion of board, or go straight through it? Also, consider geometry in your equation. Draw an exaggerated diagram of what you're proposing, imagining a board that's very cupped. When a hole is drilled through the board and into the subfloor, do you drill perpendicular to the surface of the board or to the subfloor? Regardless of which you choose, as the fastener is installed, the angle will change and the holes will become misaligned, potentially sabotaging your intent.

Hi, thanks for the reply. The flooring has already been installed. We live right on the ocean, so high humidity. Although our house does get super dry in the winter, 20%. We would have to have a humidifier in every room to keep the humidity at a constant level, so a water filling battle that we eventually gave up long ago. We have cherry floor on the first, which sees a little bit of shrinkage in the winter, but closes right up in the wetter months. The wood cured for over a year at mill, and then were stacked inside the rooms for 6 months before they were installed. There are only a few spots where they cup. They were not glued. The thought prior to install was to use the architectural nails, which my contractor said would help for the keeping the boards, down, but was mostly aesthetic, since they nailed the flooring down. I'm concerned I'm going to regret the look after the nails go down, hence plugging where needed.

jfcwood, thank you for the reply. My problem with google search is that I cant find and good representation of really light wood and nails. I'm afraid that the dark nails will really pop and change the whole look of the floor. The boards are wide 16". They were pre tung oiled 4 coats before they were installed, and a water/red wine test resulted in beading up, with no marks left after. I don't plan on doing any of the work, that will be done by my contractor, who installed the floor.