After 10 tries fiddling with various spacing for the homescreen, I finally got 8 book tiles to fit. My tiles seem slightly longer than others in screenshots, and I'm pretty certain it's because the text is slightly larger than what I see in other screenshots. And I have no idea how or where I might have changed that.
This is the spacing I used that finally allowed 3 rows of book tiles showing. Anything smaller and the top line of the search bar was cut off, or the y in Library at the bottom was missing. You can see wherever the % sign is used that it forces the tile to be slightly taller than those without the %. I had set Avenir font for the footer for the page numbers within books, could that also be what is used for the text in the tiles on the homescreen?
Spoiler:
<Patch>
patch_name = `Compact homepage layout (Glo only)`
patch_enable = `yes`
#DragonHomePageView (Search bar height)
replace_string = CDEE88, `min-height:100px;`, `min-height:089px;`
replace_string = CDEE9B, `max-height:100px;`, `max-height:089px;`
#QWidget (Space below search bar)
replace_string = CDF021, `min-height:40px;`, `min-height:01px;`
replace_string = CDF033, `max-height:40px;`, `max-height:01px;`
#MultiColumnTileView (Space between tiles)
replace_string = CDF1D1, `horizontalSpacing:10;`, `horizontalSpacing:01;`
replace_string = CDF1F2, `verticalSpacing:10;`, `verticalSpacing:01;`
#footer (Footer menu bar height)
replace_string = CDF61E, `min-height:95px;`, `min-height:68px;`
replace_string = CDF630, `max-height:95px;`, `max-height:68px;`
</Patch>
Edit: I put any font changes in the patch back to the original settings and I still can't get 3 book tiles with a % read in the description to fit going down. I still think it has to do with the slightly larger text I'm showing than others, but I really have no idea how I ended up with the larger text.