You don't state whether this is the older model, using Epic Malibu (a milky yellow), or the more recent model, using NanoShield (pale, yellowish green). So it is hard to respond, not knowing which animal you are dealing with.
If it is the newer NanoShield model, please disregard the rest of this, as I've no experience with those.
If it is the earlier Malibu model, it is probably the type of Malibu they used later, which appears to be calendered (slightly slick) on one side. The earlier Malibu used in BD tents was not.
This fabric will not show holes ('daylight') when placed directly in front of a strong light source, but does show, especially when turned slightly oblique to the light source, many small glitter points much as you describe. It also does not have the self-repairing qualities of better silnylon, so actual pin holes show up clearly.
The obvious question is whether these glitter points are weak points in the silicone treatment through which water will pass more easily. To try to get an answer, I sent a couple swatches of the fabric (purchased several years ago from Oware and Thru-Hiker) to Roger Caffin. He was kind enough to test it for hydrostatic head for me, and the results indicated no leakage until (converting to mm) around 1500mm HH. Higher than that, the leakage was, to be kind, significant.
Reading the multitude of posts on this site about 'misting' and leakage of ultralight fabrics, and while even much higher HH material can fail in a typhoon, it seems to me that 1500mm HH is sufficient in a tent or tarp for the conditions you describe. Richard Nisley tested cuben materials in reports on this site that showed well below 1500mm HH, yet many posters regularly report using such materials in tarps or tents without water coming through.
One possiblity is that those heavy rain drops you mention are causing condensation to 'spritz' from the inner surface of the tent onto you. Another is that there are pinholes in the canopy. Still a third is that some of the Malibu products are not so impervious to water as others due to poor manufacture, probably with application of the coating.
Had you access to a HH tester, you could quickly find out if the third possibility is the case. But notwithstanding Lance Marshall's excellent DYI instructions in posts to this site, you may be more like me, and without the time and/or interest in making a HH tester.
If you can persuade BD to exhange the tent for a newer NanoShield model, that would be ideal; but somehow I doubt they will do that without evidence, such as test results, that the fabric is defective. Not that that should deter you from trying. There are a number of reports of such problems with BD Malibu tents, but there are also a number of reports of surviving deluges in them; so it is difficult to draw conclusions. Roger has noted that once the Malibu becomes contaminated, especially with anything oily, the HH plummets (my word, not his), and suggested washing with a cleanser OK'd for GTX, like Sportwash; but that is a whole lot easier with a garment than for a tent.
Other fabrics, even silnylon with higher HH, will form heavy mist on the inside, particularly in colder heavy rain, even when the shelter is unoccupied, and the force of rain will cause tiny droplets of water to 'spritz' inside the tent, much as you describe.
After reading all the posts about this, on this and other sites over the years, it is hard to believe that this issue will ever be resolved. But since I've had some experience with this material, thought it might be worth sharing with you. Sorry I don't have something more definitive.
