Imo kinda mixed bag right now. Kinda understand why it's not newbie friendly for the Raid Boss event. Optimizing builds would most likely be normal for the players who reached end game, or at least can comfortably farm up enough zeny that they can sidetrack a bit. When I was new, I was quite stingy with zeny still that optimizing a build on an event where we're supposed to have "fun" would make it do the opposite. Also I'm unaware if there are actually guides for autocast WH/Chasers, didn't look them up since I'm an AM, but it would be something out of knowledge for those new to RO and didn't know those builds in the first place.
The tree sentinels part +1 on them attacking you instead of running away, that just makes them really annoying. Though I did notice some players started to corral them into corners and whacking at them from there. Or if you're in prontera, they suddenly start attacking the dummies for some reason.
The raid goddess fight is brutal I agree - though I think it's somewhat normalized now? Need some more days to check. For the ammo thing, I think it's mainly because people camp the spawn - I've seen them in the ammo spots just standing still when I tried to nab some too. AFAIK - Mirrors do have fixed spawn points, so no issues with that.
The minions are the biggest hurdles yeah. Even some end game players would find it hard to survive 4 simultaneous earthquakes (unless gtb lul) - but as the goal of the event is to just kill the goddess, you can just poke them a bit and then fly wing away when you see them casting earthquake, or just accept the death (not sure if death penalties apply in neustadt), and @go 52 again to spawn back in neustadt with no loading screens, I personally have this on my shortcut keys due to cluckers event too.
They make it difficult to grab ammo - but that's pretty much their entire point of this. Players who have anti plant protocol would focus on killing the minons, while others would try to get the ammo - I've seen people group the minions up together too so that people with AoE can kill them faster.
I don't really have anything to say with their attack speed, I find it obscenely fast, but its mainly their spider web that sticks me to the ground, and at that point I just fly wing away.
Honestly speaking, just being near someone killing the minons is already a huge help. I always feel happy when someone's near so the earthquake damage spreads to both of us and won't outright oneshot me, so even just by being there you're already helping people clearing out the minions, you could even throw some skills their way to help clear them faster