Yea more is better. I'd convince you otherwise " if" you didn't have that height restriction of 7-8 cm.
A simple calculator that determines spot size by a light's beam angle
store.marinebeam.com
8cm up and 100 degrees gives a spot size of 19cm in diameter.
Your pattern is 44 bulbs. 4x11
Your 17.5 and 15cm on centers look ok.
With that kind of design and even spacing your initial lighting "may"create a center hot spot though.
Gets much better with depth.
Advantage of floods is you can uneven space them to actually get a more even spread than you get with multiple bulbs like that.
Gets complicated doing the same thing with many bulbs.
Bulb spacing should be wider on center from the middle getting progressively smaller toward the edges. Overlapping cone thing.
See at about 10 minutes in what I mean about floods. Same concept applies for your multi bulb array.
A bit nit picky and since I haven't seen nor tested that large of an array the "imbalance" may not be that significant.
Second point is s floods can be balanced to avoid hot spots and dim spots.
Actually opaque bracing is more of an issue.
Food for thought.
Keep in mind cameras and meters are a better judge of these imbalances. Visually you may not notice them.