How to quickly understand Cish code?

Question

C++ / C#

The project has a lot of errors "memory leak" and similar hard-to-find. People decided to rewrite everything and the choice of technologies was left to me. Since I'm "on you" with C, I decided to use Go + library bindings. Now there are 3 lyama+ lines with porting to different UI and OS. The last programmer who could explain how it works quit a year ago (then they wrote more but such a thing ...). As a result, I was given 1 year for everything about everything and a budget for hiring a couple of freelancers (well, or leave it for myself if I do it myself). I tried to make a log of the launch of each function, but it did not help me much. Now I finally despaired and decided to just pick out Gui from there and no longer remember nightmares. I went to look at how the client is arranged there and found that a bunch of libraries were used and why I did not understand.
UPD.
Ideally, I want to understand the code, but I'm afraid that knowledge of C will not allow it. For this, at least pick out the UI.

Answer 1

You write

Since with C I "on you"

Not much more complicated than the same php or js.
Why rewrite so much? Isn't it easier to find mistakes?
People decided to rewrite everything entrusted to a person who from C to you ...
The problem is management. They didn’t pay a person for supporting the finished code, but they paid, it seems, several times more to rewrite everything from scratch ... Is it really that bad? )))
If you look closely, PHP and C are very similar languages ​​in syntax. I read in Wikipedia: "The syntax of PHP is similar to the syntax of the C language." And here is what they write there about Javascript "which, according to the developers, was supposed to become powerful enough to replace macros, while maintaining similarity with C"
My opinion is that it is better to learn C and just finish it, correct errors. Maybe move towards C++, maybe Qt, etc..