RJM,
Great question. There are many HS coaches out there who are helpful, and want to advance their program and relationship with players and parents. There are some that just don't care, and you need to figure out which is which in your case.
I can tell you what we did last year. We put the travel coaches name & number as well as a pro scout familiar with his ability on the recruiting forms. That is what my son was most comfortable with. My son was adamant about keeping it within those people who helped him get recruited and brought a positive light to his travel baseball accomplishments. His grades spoke for themselves.
Case and point, my son made the mistake of putting his (former) HS head coach on one of his forms. The college called the high school coach a few times but the HS coach never called the college coach back. It was a good thing that this was not one of his top choices, and we found out where that HS coach stood. The fact that the HS coach didn't have the decency to call him back tells you a lot right there. Frankly, we were embarassed for him and glad he did not open his mouth. Using your words --- "My concern is the HS coach doesn't seem to be on the same page as these showcase player's coaches in terms of college potential". Your HS coach may not be, but I know of several coaches in our district who are, and will do anything for their players.
When asked by the college (specifically), I would provide the high school coaches name and number. I would also have my son prepared to answer WHY he did not put his high school coaches name and number on the form.
Good luck!