If the issue is that the role itself doesn't have as much to do, then there's two options:

(1) Assign the responsibilities to somebody else (maybe the justices) and abolish the EC. Edit: Maybe a better option than abolishing would be to have the EC a temporary commission/organization that is staffed by the justices as needed.

(2) Expand the responsibilities of the EC in a way that would merit somebody occupying the role on a constant basis. 

 Pursuant to point (2) how an Election Commission usually works is that it oversees ALL elections. Not really sure how political parties work within TSP, but the EC could also oversee elections in political parties.

 Also, EC's are usually in charge of dealing with and interpreting the laws and regulations around elections. Therefore, it would make sense if the EC had 1 Legislator and 1 Justice as part of the commission.

 Either way, if the EC position itself will remain, maybe it should be a termed position. I'm not 100% sure how it works now, but from what I've gathered it's essentially a pool of people that are the go-to per election. Instead, have it so that whoever is appointed or assigned as EC *must* remain in that position for a minimum term of 6 or 12 months.