Shouting aside, you're putting the cart before the horse.
The point of high(er)-level languages is that you don't concern yourself with low-level constructs (did that last instruction set the carry and the half-carry? Do I jump on carry clear or carry set?), leaving you to concentrate on what the code has to do, not how it is to be done.
If you want to recode in C/C++, don't read the assembler code, read the comments next to them - they should be telling you what the code has to do.
If you don't want to recode, use C/C++ to write a 680x emulator (I know there's a 6502 emulator, there may well be a 680x one) and simply run the original code under emulation.
The only time I've ever seen a practical translation approach was a project I once worked on where the source (a lot of source) was all written in 6809 assembler, and the plan was to move it to Macro-11. An automatic translator was written (Macro-11 looks a lot like a superset of 6809 ASM), but there was still a lot of manual work to do. The approach was ultimately abandoned, but it took up a lot of time and money.