Welcome, keep in mind my opinions don't mean any more than yours, I am just pointing out a different point of view.
1. The explanation for the Brood Chamber is confusing. I thought I needed a lvl4 spider for the first free promotion. Either I'm doing something wrong or you actually need a lvl 5 spider. I had two spiders in my capital, one lvl4 and the other lvl 5, and I could only sacrifice the lvl5 spider (it was the first sacrifice).
Then you get the Brood Chamber in the list of buildings of the city menu:
Brood Chamber.
+Spider units get 1 free promotion.
+Upgrade requires Nest Population of 8.
+Upgrade requires Giant Spider of Level 5 or more.
That "Level 5 or more" is "6 or more". I can only go for the second free promo with a lvl6 spider, it won't let me sacrifice a lvl5 spider.
bug already reported and fixed, New Patch hasn't come out so we see that fix yet
2. The event about the Haruspex asking for a sacrifice for mother pops up too often. At some point, it pops up every 4 or 5 turns. Is this intended? What are the requirements for the event to show up? I'm guessing you need your cities to be happy to avoid it. Am I right? Which in practice means you need at least happiness 8 to get a poulation 8 capital. Isn't that little bit too much, taking into account you get that event also for other cities apart from the capital?
I havn't played my Archos past turn 150 yet but I never got this once. (maybe I didn't have unhappiness?) Us the button on the food line to prevent growth that cuases unhappiness.
Yes you need 8 happiness for pop 8 city, but resources and buildings make it not very hard to get.
3. Shouldn't Raghodessa be changed? The first level, "attack multiple times per turn" is worthless unless you researched Horseback Riding and got a mobility promotion. Sure, HR is an early tech but definitely not a priority for the Archos. It would just make sense that you get +1 movement before you are given the chance to attack several times per turn.
Doesn't that (or their next level) add +1 movement? Alternatively being on roads, or using an item to increase movement can effect it too. But yes Horse riding definatly helps. This is my faovrite of all the spiders
[/quote]Water spiders look nice but only is specific situations. Maybe they could get a +10% strenght at first level to make them more generally appealing.[/quote]
Maybe, but I don't really have an issue with them simply being a specialized not normally used unit.
I don't know how, but I got a spider with 2 different specilizations: Argyroneta and Textus. How is that possible?
another reported and fixed bug, just waiting on new patch
4. I really think the problem with spiders in the later game is not the fact that they become weaker in comparison to other units. The problem is that it isn't rewarding, not even very thematic, that you've been caring for your spiders for the whole game only to find you will outdate them with the little effort of building a higher tier unit in a city.
I think more spiders could be sacrificed. Right now, it goes up to lvl 7 and then four free promotions. If I'm not wrong, the last sacrifice is a lvl 7 spider at city size 16. To that I would add a second lvl 7 spider at size 18, giving +1 movement to newborn spiders; and a third lvl 7 spider at size 20, giving +1 strenght.
Now, that's strenght 7 spiders with 4 free promos and 2 movement. Yeah, they look too powerful. But then again, how long does it take to level up 6 spiders (3 of them to lvl 7) and then grow your city to 20 (with that annoying "sacrifice for mother" event...)? A little while. By that time, other civs can probably mass-produce other units of similar strenght. Is it easy to get those spiders? No. Is it rewarding? Yes.
This is exactly why the recent changes to the spiders happened (and this thread started) Personally I would like to see more promotions added so they can scale higher when highly experienced.
Did you cast the ritual Feral Bond? It adds the Strong promotion to all animals, including all of your living spiders +1 Attack and +1 Defense. Late game thing tho.
And to add up to mix, Haruspex and Spiderkin should be made weaker and given the chance to "ride spider" or something like that. They would be something like 2 or 3 strenght weaker than now, but if you "add them" to a promoted spider, the resulting unit would get the spider's promos and be slightly stronger than usual druids and beastmasters. Of course, a heavily promoted spider born in the perfect nest plus a Haruspex or Spiderkin would make a very powerful unit, but you only get 4 of each of those (and you won't have that many very powerful spiders).
I don't know if it's doable, but it would be great. Most barbarian civs are better at the early game. I wouldn't mind something different for a change. This spider-haruspex-spiderkin based Archos would work at the early and mid-late game, I think.
Did you read this thread?

suggested a few times. He is considering allowing the Haruspex to combine with a spider to make a better over all unit, with strengths from both units for instance.
Off-topic:
I got a bit lost when downloding the mod. I didn't know if I should get a specific FFH patch, or if FF was compatible with patch Z, and didn't find anything about it in the forum.
FF only really NEEDS FfH base with no patch. the FfH patches are contained once you patch up to current FF patch.
As there's no manual from FF (which I understand, because it's hard to keep track of all the changes), a fixed thread for each FF civilization could be a good idea, with an opening post where tweaks to every civ could be explained.
http://www.vehemence.org.uk/wiki/index.php/Main_Page
Work in progress