JC,
I think the list of potential candidates provided is a reasonable one to start with.
In light of the social, business and golf stature of those involved with the creation of Seminole, it's unlikely, though possible, that unknowns were brought in to tender a design.
David Moriarty's research that found the ship logs chronicling Crump's overseas travels was a marvelous bit of research, one disproving a long held myth.
David and Tom MacWood might be able to pinpoint whom amongst the premier architects was in South Florida from the time the land was purchased until Ross was commissioned.
But, there's another possibility.
That possibility is that there was NO other architect commissioned or consulted with, and that Ross was the only architect involved with the project.
Perhaps the idea to level the western ridge was an internal one, springing from the mind of a founder or interested party or from one of Ross's Associates like Walter Johnson, Walter Hatch or J.B. McGovern.
As you know, the western ridge is a massive feature running the entire length of the property on its western border.
Leveling that ridge would be an enormous undertaking, in time, manpower and money.
In addition, that ridge provides wonderful views to the east, views that a prudent person would want preserved.
"The Story of Seminole" indicates that E.F. Hutton wanted to preserve those views, ergo, the ridge, and, he was THE man.
While there are references to routing sketches by the two anonymous architects, I wonder if they ever existed.
If they can't be identified or described, then how does the author know of their existance ?
It may be one of those unsolved mysteries unless Dr's Moriarty and MacWood are brought in.