I don't know what I did ... except maybe Springtomize doesn't work on 4.3.1 RedSn0w jailbreaks? ? ?
All I did was download it and it works fine. Granted, all I use it for is to use a custom number of icons on my springboard (I use six). I haven't tried everything else because I already HAD other tweaks that would do what Springtomize does. And, TBH, just having the ability to easily change the number of icons per line was enough to justify the cost of the app to me.
Sorry I can't help you better, but I don't really know why Springtomize works for me. Maybe it is 4.3.1 ... or maybe we should do a tweak comparo to see what's the same or different...