I haven't looked at climate yet so tundra is nto my fault
As for lowlands, I must tune again to try to get some more hills. What map size do you use? I know there were sometimes too many flatlands in the civ IV version on big maps so I guess the same problem can be present here too.
I'll may be tweaking the starting positions someday in the future but that's not a priority.
The lowlands scale with the mapize. Not a suprise.
The tundra starting is a problem that only affects playing with tectonics. In contintents maps i hardly ever start in tundra, Startingbias enabled or not. So i guess that your (great ) mapscript somehow interfers with the starting positions?