Mix half-dollar sized crushed and smaller stone in the run, and it will keep the textile pinned down to the soil slowing the water more. It will be critical to prevent too much water from under-running the fabric. Make the run is 3X-4X wider so when you get some heavy rains, it can hold it.

I had the same issue when my pond was first dug, and over the years the erosion exposed rock that was embedded in the soil so the erosion slowed down considerably. I did what you did without the fabric and more mixed stone, but it wound up causing problems when we had some flooding since the flow exited the area I filled with stone. It made a mess. I since made it wider and manually excavated and placed stone, clay, etc to force the water over large stones. Now vegetation is holding things together pretty well.