Based on the MSDS's for those products, the InvisaTread is glycolic acid and the TractionWash is a neutralizing solution of sodium triphosphate (STP) and sodium silicate with surfactants. Basically what the InvisaTread will do is mildly etch the surface of the travertine making it more rough so, in essence, a chemical roughening process. The degree of roughness is controlled by how long you let the solution sit on the surface. I would make sure you fully understand the application process as it is pretty detailed and requires buckets, chemical spray spreaders and shopvacs to help quickly apply, spread and remove the chemicals. Their warning to test it out on some old tile pieces first is quite spot-on, this is not something you should try on a whim.
My main concern with this product would be uniform application as it would seem to be quite easy to over etch some areas, and others not enough. I'm almost certain this ill change the texture and polish of the travertine surface and may dull the tile permanently.
Also, you DO NOT want to get glycolic acid in the pool. Glycolic acid will be oxidized by chlorine to oxalic acid which is nephrotoxic (bad for your kidneys). While the amounts used may or may not be at toxic levels, I would always be wary of spreading chemicals around the pool.
Just my opinion. Maybe someone has some actual experience with this product.