If you'd amended the source, then it wouldn't be the same version and the license would be invalid. If you want to use the perpetual license, you can't do anything with the source.
> Epic grants you a non-exclusive, non-transferable, non-sublicensable license to privately use, reproduce, display, perform, and modify the Licensed Technology in accordance with the terms of this Agreement (the “License”). This means that as long as you are not violating this Agreement or applicable law, you can privately use the Licensed Technology however you want. If you want to share the Licensed Technology or anything you make with it, Sections 3 and 4 below address when and how you can do that.
In section 3/4 it goes to that you can compile your game and give the output to outsiders if you pay the roylaties when applicable or share them royalty free on epics github (basically you make a pr to merge your stuff upstream) or on unreal marketplace (sell it)
I'm not intending to be defensive (I'm sure there's loads of people on here with more knowledge about licensing terms), but usually a corrective post is something that we can learn from. Just saying something is wrong with no more info seems against the spirit of HN.