Ok so let me try to make this as short as possible. We had our main floor refinished ( 3/4 thick tonge and groove american cherry) and some new american cherry added where we used to have carpeting. They did a great job reweaving the new wood and resanding the whole floor. Then they applied one coat of clear Synteko (matt/sand finish) and let it dry. Everything still looked good, floor was still rough. But after buffing and adding the 2nd coat we saw waves in the floor. Like either the sander had a bad belt or roller.

We showed the contractor and he agreed that he is going to have to resand and refinish. So he resanded at a 45 deg angle so the machine wont follow the waves and then carefully sanded straight. Then he did one coat of the same product Synteko matt, buffed, and then 2 more coats 1 day apart. The waves are gone. But now we are seeing a lot of other defects. We can see some lines in certain areas how the last coat was applied. We can see where they had to sand by hand ( corners for example) they did a terrible job and did not sand properly.

Now this first floor is over 2000 sq ft. So I really dont want the whole first floor resanded. Can someone just resand and recoat with the same product the problem areas and blend in with the rest of the floor? How about the lines from how the last coat was applied, can that be buffed out? Any feedback would be greatly appreciated.

The difference between a great job and so-so is the details. If there is any touch-up of the poorly done corners or the rivers in the finish, you will notice a difference in the gloss level of the finish even if the exact finish is used.
Scraping to bare wood to re-do the corners will require two coats of finish. A river where the finish did not flow evenly can be scraped smooth with a sharp scraper to flatten the surface. Some people use a random orbit sander to make the surface smooth on this repair.
A final coat of finish over the whole floor will make everything right.
You may offer to pay for the materials needed for the third coat, approximately $30 per hundred square feet, as an incentive to get the work done right and give the floor a thicker wear layer without changing the color. That would be more than fair.

Pete A.
Thank you for the advise. So if I understand you correctly just the trouble areas we can resand and apply 2 coats of finish. Then the last coat of finish over the ENTIRE floor so everything looks like one floor. Thanks!!

Any other replies or opinions would be great appreciated guys. Thank you.