Hi
@Wchu98 and welcome! It's never too late to introduce yourself and get your hands on open source development
If you plan to work on one of the items as summer project you should hurry up, though. There is not much time left for many iterations of you proposal, so start now and give us something solid to base a discussion on.
I can only advice to focus on a single item due to time constraints. There is a lot of content about Ligth&Shadow in the forum, and its implementation will touch a lot of other modules and systems. The benefit here is that you might be able to reuse things, but on the other hand there is much you have to learn to get a good overview.
The other topic, improving the Create World Screen, is more focused on a single item and does not involve a bunch of modules. This one is more centric to the game engine, so probably need to get a better understanding of our architecture and the code base in general.
In any case, get started by checking out the project, getting it run from source and try to work on a small bugfix or change. Given the beginning time pressure, looking into the preview image task might be the better option. Familiarize yourself with the related code, and I'm pretty sure you can find a bug to fix or some little feature to add
Looking forward to a proposal!