TE recommendation.
When converting an AH2 terrain, I suggest that the rotation of all Group Masters be set to zero except for Ports and those should be checked for 0, 90, 180 and 270 degrees. To support this, I point to blksea and blkseaw, not because I'm picking on them, but because that's where I see the problem in extreme.
I was checking something else and noticed that many of the field icons are upside down. V-bases are the easiest to spot but airfields show upside down as well so presumably some towns and maybe factories are also rotated. In all the cases I checked, the square tile object isn't rotated precisely and it opens the terrain to water along with mismatching the surrounding elevations. If the builder still wants to rotate them after the conversion, he still could.