Your terms of service allow you to do anything with a mod even if the user deletes their mod.
Under twitch, the following conditions applied to mods:
"(ii) With respect to User Content known as “add-ons”, “maps”, “mods”, or other types of projects submitted through CurseForge.com or related sites (the “Submitted Projects”), the rights granted by you hereunder terminate once you remove or delete such Submitted Projects from the Twitch Services. You also acknowledge that Twitch may retain, but not display, distribute, or perform, server copies of Submitted Projects that have been removed or deleted."
Overwolf's Terms of service have no such exception:
"By submitting or posting such Content, you grant Overwolf and its successors a worldwide, non-exclusive, royalty-free, perpetual, sub licensable and transferable license to use, copy, distribute, transmit, modify, prepare derivative works of, publicly display, and publicly perform such Content on, through or in connection with the Site or Services in any media formats and through any media channels, including without limitation, for commercially promoting the Site and Services."
Overwolf does not need a perpetual license to modify or prepare derivative works of Mods. Additonally, overwolf only needs a non-exclusive, royalty-free, sub licensable, transferable license to copy, distribute, transmit, publicly display, and publicly perform the mod. Overwolf should be allowed to retain, but not display, distribute, or perform, or serve copies of mods that have been removed or deleted.
Please modify your terms of service to include language similar to Twitch's terms of service. I'm sure most mod authors don't want companies to have the right to do anything with their mod.