The EULA is definitely the governing document, and it does address IP ownership. In Section 10:
Epic or its licensors own all title, ownership rights, and intellectual property rights in the Engine Code and Content. You own all rights in the Products you develop under the License, other than the Engine Code and Content, Third Party Software, and any Contributions.
I had a question or two regarding the terms and conditions of the license(s) granted surrounding the usage your software. Primarily this is in relation to the ownership of any final products produced within your platform-- I noticed your EULA discusses source code modification and distribution (i.e. tools, etc.), but do you have a more fleshed-out contract/license agreement that details the ownership of the intellectual property developed on your platform (i.e. games, etc.) that are not just direct modifications to your platform source code?