Hello @perlman. Ideal for your application is a bit subjective.  As with wheat, the other aspect is the quality, or functionality of the protein.  You can read more about spelt on BAKERpedia here:  https://bakerpedia.com/ingredients/spelt-flour/

As you are making crackers, I would conclude that a lower protein would be more desirable, as in the cracker industry where wheat flour is used.  Traditional wheat crackers are produced predominantly using soft wheat flour that is between 9-11% protein, most crop years.  Various growing conditions will impact protein quantity and quality.