If my math is correct, Forge Pass gives you 950 of the mats needed for the 5-6* items. At 5 per forge, that means you can forge a total of 190 of them with the Forge Pass. Add the six you get for reaching level 50, and you get a total of 196. Double that by the fact that they normally run this twice, and you're at 392.
There's a 50% chance that you get a 5*, so we'll assume half of those 392 are trash. Down to 196.
We'll also be generous, and say half of the rare ones end up being trash. There's a 35% chance for rare, so we'll say 17.5% of those remaining are trash, leaving us with 162.
162 is quite a lot of crafting. My guess is that you'll easily be able to get three full, usable sets out of 162. You could very well end up with more. In comparison, FTP get 20 total. Reduce by the same above math, and you end up with a total of about 8 potentially useful items.
That sounds very much P2W to me. Especially considering those artifacts will never lose value (barring some more crazy power creeping). I stand by my original statement that this is an absolutely terrible set for them to add.
Your math checks out, as I've gotten precisely 3 usable Bolster sets, and I haven't crafted the last part yet, so that's likely one more. With charms and glyphs I made one solid Brogni build, and two on Vogoth and Minaya which are just HP focused.