Hello Ahanu, Thanks for sending the file. I had a good look at it. What we confront all the time when engraving is that music often simply does not fit the page. I can't find any way to make this piece fit on two pages at that staff size. The fact is, it's simply too long. Personally I find it readable if you leave out system-count = 20, but I understand that may not be your preference. If you set systems-per-page = 10 (and remove system-count) it looks good and spacious on three pages. You may have to compromise with that. You could reduce the staff-staff spacing, but I think you don't want that. Apart from these ideas, I am at a loss for a solution.
I encountered a similar problem just recently with a 300 page string quartet I am engraving where some dense pages simply ran off (its complicated to explain). In the end the composer suggested going smaller, and it all looks fine and readable. In my case also, there was no other way than reducing the staff size globally. Andrew