The druidic and shamanic secrets got overwritten/removed at some point, and although there are secrets for beasts and plants for druidic magic I have not replaced the shamanic secret/school as of yet.
It is possible to make a secret only available to a single race but there's nothing preventing other civs' deities from spitting out the appropriate secret slab and then the would-be practitioner failing to use it. If you split the secret into two syndromes, one which affects everybody and grants immortality, and one that only affects dwarves but grants all the actual powers, then that would probably work in WG and during play.
Immortality is the only goal currently which will lead people to pursue secrets, so changing it would just mean it never actually shows up in play.
The mod as it exists isn't meant to be divied up quite that much yet, I'm still compartmentalizing things, but if you deleted everything else, then of course you'd only be left with the desired druid secret.
To do that, delete;
All the creature files besides creature_spellcrafts and creature_spellcrafts_druidtrans
The added entity files so the only thing left is entity_default
the added inorganic files except inorganic_spellcrafts
the added interaction files except interaction_spellcrafts_base, interaction_spellcrafts_effects, interaction_spellcrafts_spheres_a-e, interaction_spellcrafts_spheres_t-z and interaction_spellcrafts_summons
delete all the reactions files, since you wont be using reactions.
Also delete the plant_spellcrafts file
Then in interaction_spellcrafts_spheres_a-e, delete [INTERACTION:SPELLCRAFTS_SECRET_SPHERE_BIRTH] and everything after it, and in interaction_spellcrafts_spheres_t-z, delete everything before [INTERACTION:SPELLCRAFTS_SECRET_SPHERE_TREES], and then delete [INTERACTION:SPELLCRAFTS_SECRET_SPHERE_STORMS] and everything after it. The only things left then should be [INTERACTION:SPELLCRAFTS_SECRET_SPHERE_ANIMALS] and [INTERACTION:SPELLCRAFTS_SECRET_SPHERE_TREES] and their associated info. I think.
Then edit the entity_default.txt file and below [RELIGION_SPHERE:WEALTH] add [RELIGION_SPHERE:ANIMALS] and [RELIGION_SPHERE:TREES], which should make the dwarven entity produce deities of those spheres which will have a chance of sharing those secrets. Then you'd have to edit the actual secrets so only dwarves can learn them, and that would entail adding a second effect, so copy this part;
[I_EFFECT:ADD_SYNDROME]
[IE_TARGET:A]
[IE_IMMEDIATE]
[IE_ARENA_NAME:Floral Druid]
[SYNDROME]
and paste it again below [CE_ADD_TAG:NO_AGING:NOT_LIVING:START:0] so it should then look like this:
[I_EFFECT:ADD_SYNDROME]
[IE_TARGET:A]
[IE_IMMEDIATE]
[IE_ARENA_NAME:Floral Druid]
[SYNDROME]
[CE_DISPLAY_NAME:NAME:flora druid:flora druids:flora druid:START:0]
[CE_ADD_TAG:NO_AGING:NOT_LIVING:START:0]
[I_EFFECT:ADD_SYNDROME]
[IE_TARGET:A]
[IE_IMMEDIATE]
[IE_ARENA_NAME:Floral Druid]
[SYNDROME]
[SYN_CLASS:BIO_IMMUNE]
[CE_CAN_DO_INTERACTION:START:0]......
Then leave the upper I_EFFECT as-is and add [SYN_AFFECTED_CREATURE:DWARF:ALL] below the SYNDROME line of the second one. This should allow any race to acquire the title and immortality, but only dwarves will gain the powers.
This could all cause lots of additional errors, of course, and I have tested none of it, but just in the 15 minutes it took to look through the files I think this is all the work necessary to strip it down to where those are the only major effects you'd encounter. And like I said, there's no shamanic secret at the moment, so plant and animal druids are all you'd get.