Hey @Aseeef, thanks for the suggestion, and sorry for the delayed response! After some discussion on Discord, it was decided that delayed commands are probably outside the scope of the CommandAPI, so unfortunately this will probably not be added directly to the CommandAPI. The CommandAPI is focused on providing an interface for command features that are hard without Brigadier or NMS code. Delayed commands are possible using typical Spigot API, so they are probably outside of that scope. There are also many different ways developers may expect delayed commands to work, so it would be difficult for the CommandAPI to implement one solution that works for everyone.

However, to help people who want to create delayed commands with the CommandAPI, PR #460 is going to add an example project to the CommandAPI that shows off some solutions. Hopefully, that example project will help guide developers in creating their own system, or they can just copy the code :P.

Previously, a command API I built for my plugins used this

The PR doesn't actually have any examples yet, though I do have an idea of how I would implement a delayed command. If you think that system you used before can be adapted to the CommandAPI, you're welcome to add it to the PR!