"more flat" is a correct and usable phrase in written English.
It is used to describe something as having a flat shape or quality. For example: "The surface of the lake was more flat than I expected."
"The high street is more flat.
"When it was first done, the world was more flat.
"No more flat, boring, static photographs," they promise.
Badoit would make a terrible float, more flat than fizz.
People say technology has made the world more flat.
The adsorbed protein-like chains trend to be more flat when adsorption interaction energy becomes strong.
For people to buy more flat-screen TVs on their credit cards?
But Mr. Tang has added more flat-panel television screens to cope with the whole Linvasion.
I was more flat-footed than usual and willing to take more chances.
Mr. Quaid's slow, droning line readings make the writing sound even more flat-footed than it might otherwise seem.
Under legislation already in place, the additional State Pension is becoming less earning-related and more flat-rate over time.
