Someone has already posed an update for that Addon (
https://www.esoui.com/downloads/info...er-Update.html). No sense in re-inventing the wheel. Usually I attempt to contact the original author to see if they are going to update it. If I don't hear from them in a couple weeks, then I will double-check there is not been a different release by someone who has taken over the project.
I had one addon where I made some fixes (Removed libstub and a few other minor error fixes), but then the addon author returned several weeks later and updated the original. So I took my fixes back down (blanked it out and labeled it as discontinued and pointed them back to the original).
I learn a lot by just looking over other people's addons to see how they work, which API functions they use, etc. I find it is usually the best way to learn. I have a few "simple" addons that are just learning projects that I have shared, so if you are looking for some very basic pointers, those may help. Search for the word "simple" and you will see a lot of different examples to study.
If you want to take over an abandoned addon, contact the administrators and ask to be added to the development team for the addon in question. I recently did that for ScrollListExample.
Edit: I see you were referencing the update I linked. Sorry. I think someone has recently released a pledge rotation library, so maybe DarkPhalanx will link that in when they do the next update. I suspect that some addon authors only check on their addons when major api changes happen, so there may be a wait.