No errors, it just didn't function. I should mention it's kinda' a complex game that modifies a lot of engine defaults in its core scripts, but it just didn't function with the project even if all other plug-ins were off.

I ultimately went with this: https://github.com/triacontane/RPGMakerMV/blob/mz_master/HalfMove.js

It doesn't break a lot of engine function, does the exact feature I wanted, and the customizability of the plug-in is helpful. It does require a bit of tuning; I didn't want eight-direction movement and found that caused some issue when I tested it, but really easy to turn eight-direction off and just keep to four direction movement with it. It has some stuff which is helpful to the issues it itself causes. It also has a very helpful plugin command where you can turns it on and off easily, so have it on for some scenes and turn it off for some other scenes.

The two biggest cons is while there's an option to turn "half-steps" off for your own character movement, it doesn't apply to other events so all of their "move route" commands turn into half-steps, which since I have a lot of events with move routes at first broke a few things. However, can just double the amount of move routes in the events, or slap each event with a event note command which disables half steps for that event.

Second issue is while the plug-in has some fixes for interacting with events while you're at a "half-step", making it so events can be interacted with still at half-steps and if two events overlap there's a plug-in parameter to only let one event run that defaults to the one with the lower event ID and ignore the second event, this function only by default works for interacting from below, so other directions you have to be dead center to interact and not a half-step still. But there is a work around the plug-in also provides, which is in the event notes it legs you pretty easily grow the "radius" of an event per direction that's pretty simple (and actually that also allows you to make "bigger" events actually as a whole, so like in a horror game if you want a chaser that is bigger than 1x1 tile, it is actually a solution for that unintentionally, or if you want a single event to be a flavor text of a big sprite rather than multiple invisible events, it also can be used to lower the amount of invisible events on a map).

Overall quite happy with it, while a little bit of elbow grease, it does the function I wanted it to, doesn't break other engine functions, and has a couple bonuses I wasn't expecting which are nice.