1) There aren't going to be any more fixes coming from Firaxis. Islam Plates sounds like a modded map type; you might have luck getting the maker of that mapscript to fix it if you can contact him/her.
2) 9-year necro!
2) jajajjaja
to the thread:
high sea: 20% of the world will be land
medium: 30%
low: 40%
meaning low sea level maps have twice as much land than high SL.
beeing ratios:
20:80
30:70
40:60
high sea will also have 4 ocean + coast(O+C) tiles per land tile, while Medium will have 70/30= 2.3, and low SL will have 60/40 = only to 1.5 tile of O+C tiles per land tile.
Also, there will be 20/80= 0.25 LTiles /O+C tiles; 30:70 = 0.42 LTiles /O+C tiles and 40/60= 0.66 =2/3 LTiles /O+C tiles, respectively to each sea level.
If:
Total land will double with low sea level compared to High SL, and Land tiles will be 2.66 times more common. ( 0.66/ 0.25)
Medium sea will be near a mid point between the two extremes analysed above.
As Med. SL will be 1.5 times that of high sea and 0.75 that of low sea, due to
30/20 for (M/high) SL and 30/40 for (M/L) Sea Level
As you might have realize, independently of the map script, each sea level changes gameplay notoriously.
In fact, you can have more game experiences than N° of maps * sea levels * climates * the results of every other combinations of different settings.