This is actually quite common and not unexpected.
As software becomes more complex (and games are *very* complex pieces of software), it becomes harder and harder for individual programmers to understand what effect other components have on the code they change and what other components might be effected by their changes - simply because of the large number of interconnected components and the limited space in human working memory. "Modern" software development practices (OOP) also compound the problem by encouraging designing components to "reach into other components" to manipulate their state (although OOP tends to not be used too much in games). On top of that, RPG rules in general are complex and force these interactions by design (think of something like rangers doubling their bonuses to survival etc. when in their favorite terrain, which requires the skill check code to be able to ask the map what terrain we are in, etc.). If time pressure is added to the mix, the kinds of bugs you see in patch 8 happen.
Just give them time to refactor (reorganize and untangle) their code.
