The inspiration on Discord is on purpose. I find it very easy to switch servers and be active in more than one at the same time. So, why not to apply this concept to forums?
Im glad that you liked the UX. You can experience it in first hand by downloading it here DisCorkie
Removing the customisation initially was a strategical decision. DisCorkie is developed by just one dev (myself) and I decided to focus on the UX, basic features and make it available on all platforms.
Once the project has achieve a good level of maturity, the forum customisation will be on the roadmap.