yes, find out WHICH tiles they are, and make new ones to match.
I can tell you right now, they're ***50.tga, a just by looking at their positions.
Might want to make see if they're city/sea or farm/sea. Zoom in on the missing tile, and hit (whichever key it is for "info" and it'll tell you what tile it is.
you (usually) cannot simply copy/paste tile statments form one data ini to another, due to the differing naming conventions, and positions in data ini, which are writtein to the TFD.
Which means, they should only be added via the TE. Which will require the full texture list ini for that terrain.
terrain work is the single, hardest thing around (after cockpit modeling). It is NOT something the inexperienced should attempt.
also, to lower the frustration index, you might want to get in contact with Gepard, who built it, and is working on a camaign mod. (see Missions and Campaigns Forum, "Panslavic Wars" thread. Perhaps he's updated the terrain?