I haven't heard of anyone else using MS Publisher to emboss on the Tiger. I know that some people use Microsoft Word and others use Adobe Illustrator. Personally, I use CorelDRAW.
There are just so many variables that could be causing your difficulty!! If your solid 2.5 lines is black, you could try using a gray color, which will not emboss as high.
I suggest that you try out a sample of page of just lines. Make them various thicknesses, and vary the color from black to several shade of gray and emboss it to see how that works. Generally, you will have to do the same thing (on a different page) with texture samples to see how the embosser handles them as well. I really am not familiar with the settings that are available in Publisher.
You should have white space behind the numbers if they are situated on top of the background grid. Are you using the Braille29 font at 29 pt size for the braille labels? That is essential when using the Tiger.
Hopefully if anyone else has experience with Publisher, they will post something that may be of help to you. You could also
Keep trying. Good luck!