ok but ... why ?

Wouldn't it make more sense to rename the files to the names of the elements?

I don't know why "ICE" is ICEI.cpp. Others like H2.cpp are like that because H2 used to be the actual name of the element. The name of the element file is meaningless so we can easily rename it without affecting the game. But renaming an element does have effects because some of the new names don't make sense, or were changed for good reason (like WWLD)