Elvenstats can only report what it's given directly and from that attempt to calculate other things. Players go inactive all the time and there is no probably no direct statistic given for that....the data only shows the weekly score and thus movement. In other words, "active or inactive" is calculated and elvenstats has decided to say "may be inactive" based upon some formula.
Now for the fun part. When you display information in something like elvenstats, you can do it one of two ways. You can generate it from "raw data" on the fly, or you can, when receiving raw data, generate it and write it to the file for permanent storage. The first provides it when it's needed but puts a burden on your server by having to calculate it every time it's needed, the second calculates it once and stores it so it puts a burden on your storage space (especially if you have a lot of things you are calculating from the raw data). So it's a trade off. I suspect, in the case of "active/inactive" it's not stored and thus would need to be calculated when needed. If you are looking at a list of potential members the system could stop and calculate their active/inactive status but it would save a lot of processing power to only do the calculation for the ones in which you have interest. Remember, there may be hundreds of users at any one time (or ten or one or none, ??).
So, if the list is full of "inactive" players, it's a pain, but it's understandable. And the same may go for the fs part, but that may be more due to the idea that it's possible to recruit from other fellowships (though not socially kosher) and thus, one would imagine, some players would not care if they were in a fs or not. Thus, the list does not filter those in fellowships out. Just a guess.
AJ