Not really sure what your setup is to take RGBHV from PC to TV, but looks like you're having issues getting proper csync out of CRTEMU.
Don't forget that PC sync voltages are much higher than what the TV expects. You should put some resistors (~470 to 1000 ohms) on the H+V lines to bring the voltages down.
When you join H+V syncs by just connecting the wires, which I guess you've done, you get what I call "smushy csync". It is sufficient for most old CRT TVs, but not perfect. The main effects are seen around the vertical sync/retrace period, where the TV's sync tracking can get lost. Some TVs don't like it at all, some TVs have a squiggle near the top of the screen as the TV works things out, sometimes other symptoms. Even so, some TVs are OK even with no vertical sync input at all, so long as the rest of the signal is fairly predictable.