avoid loading anything into %SYS unless it is a class / routine that starts with a "z" ... everything else will be overwritten when you upgrade InterSystems IRIS.  If you ever want to class to be available to all namespaces, you can call it %z<some name> and load it into %SYS and then you can call it from all namespaces and it should survive an upgrade.

Let us know if you got it working!

if you import this class into IRIS you will then be able to run the methods.  Look up the docs for $system.OBJ.Load() .. you will load and compile the class and the. you can call the methods like this:

Do ##class(User.Ready.ConvertCSV).ConvertN()

(I assume you cut out the actual logic of the methods when you pastes it above as what you pasted is incomplete)