There is a problem with digital gauges, that can be added in the hud editor (screenshot below). Everything works fine if there is only one digital gauge. If i add a second one, select the area of the hudtexture that shall be used and move it to the place where i want to have it, everything is ok. Then i save it, leave the game, check the entries in the ini and they are all ok. Now, when i load it again, the second gauge uses the exact same position on the screen and also the exact same hudtexture coordinates of the first gauge, even if the ini entries are different. But both gauges work as they should. If i add a third gauge it's the same, it also uses all settings from the first gauge and so on. It is impossible to use more than 1 digital gauge, because they are all on the same space and look identical, but as said, all gauges work properly.
The stock HUD Multi Dial has both a tach and speedo gauge. Maybe have a look at its ini to see how they did it. I know the person making the SMG HUDs reported the same issue as you. Good luck and bring on the new UI!
You have to use the devmode for it. Start the devmode, click race, click race again to sit in the car and then, in the green menu screen, select "Enter HUD Editor".