Transmitting frames with Triple-Speed Ethernet MegaCore over Ethernet/RGMII

Your snapshots are impossible to read, probably because the forum automatically reduced the image size. Try and put them in a .zip file or use the png format, which IIRC isn't modified by the forum software.

From what you are saying I assume that you are not using a CPU with the standard Altera driver? I seem to remember that the TSE behaves a lot better if a proper SW reset is done before using it. You can have a look at the Altera software driver, see how they do it and reproduce it in your project. IIRC this reset procedure takes a bunch of clock cycles so you must be sure to wait for it to be finished before doing anything else. The TSE also needs all its clocks (both on the Avalon Stream side and the [RG]MII side) for the reset procedure to complete correctly.