Why not just can it plain? That way you can use it in multiple ways after opening, add whatever you want to it then. Since it is already going to be mushy when thawed that would be the best option. Plus that way you don't have to mess with the Clear Jel to make it into pie filling. You can add any thickener you want later.

Dave

PS: But yes you can sub the cherries if you wish. You can also mix in cranberries.

Here is a link that might be useful: NCHFP - Canning Stewed Rhubarb

I canned up about 50# this year, from fresh rhubarb, just cooked it til tender (don't know if I had to, or could have raw packed it). I'll be straining the juice off for jelly and pulp for jam later. Or maybe pie with the pulp.

This is from the Ball Complete Book and it's delicious: http://proverbsthirtyonewoman.blogspot.com/2013/05/canning-rhubarb-strawberry-pie-filling.html