Profile of SkyWolfy

So i begun learning how to mod recently, i've set up my Mod Manager by following one of the more popular tutorials. Downloading SDK from source from the author which was one of the official sources for SDK Flex atm and got Java aswell.

Was working on and testing my mod for past 3 days and today i decided to add custom icon i made.
Followed an tutorial how to set it, checking several others and some forum discusions to make sure before hand.
First i created Data/ui folders manually and added them to my mod build via mod builder, with my icon there. Wrote the 'ModIcons_(Modnumber)_(iconname)' to the unit i made it for, saved and clicked 'build'.

It took its time as usual but right before it finished i got 'mxmlc.jar missing' error from SDK folder.
So i checked the SDK folder, found a file named 'mxmlc-cli.jar'. Then i decided to look for other sources of SDK non-having this file aswell and re-installing Java aswell to make sure.
So i just renamed the 'mxmlc-cli.jar' to 'mxmlc.jar' and after doing so, i kept getting 'Error building modfile.mod: C:\Program Files (x86)\Java\jre1.8.0_321\bin\java.exe failed with exit code 2.'.

... and as i have still little experience with Mod Builder, and seen lot of people having issues regarding the same error. I dont even know if its still SDK/Java issue or some issue regarding the placement of the icon or something.

So here i am asking for help, i would really appreciate any help or knowledge regarding this issue or if someone has SDK flex files that are working as i dont know anymore.