So you guys still can't write to the cache partition?
If so try changing this line on the MAKEDEV's
mknod -m 0666 /dev/mtd/mtd4 c 90 6
to
mknod -m 0666 /dev/mtd/mtd4 c 90 8
I stated this before but never looked at the push, but I was also uncertain about it... Sorry about that.
But maybe the cache getting corrupt is something different... Kinda like the losing of some widgets on the Android home screen?
As for not being able to write to the recovery partition are you still using the same starting place as before. 0x4000000?
I won't be able to test for a while today for I forgot my phone at home.