I'm on a 1.12.2 server with my friends, 12 days have passed on it with literally nothing happening: no tornadoes, no storms or even rain. Tornado and storm chance is set to high and the minimum days until storm is 5. We have other mods too:

this is server and storm are so much common and it's latest version with no issue

So I ran your mods with a few exceptions:

• RecurrentComplex has been updated
• Firstaid has been updated
• CreativeCore updated 4 days ago
• Chocolatequest is updating a lot so I have the latest alpha version.
• Antique Atlas has updated
• Added the Recurrent Complex Antique Atlas Compatibility Mod.

On Singleplayer, I had no issues getting storms to spawn in naturally and forcefully. I also had no issues with config changes to weather2 because I had 7 storms running at once.

It sounds like you really want rain but also want tornadoes every once in awhile. This requires using the advanced configuration instead of the EZconfig.
I:Player_Storm_Deadly_TimeBetweenInTicks=120000
I:Server_Storm_Deadly_TimeBetweenInTicks=120000
I:Storm_OddsTo1OfLandBasedStorm=2
I:Storm_OddsTo1OfOceanBasedStorm=2
I:Storm_Rain_OddsTo1=5
I:Storm_Rain_Overcast_OddsTo1=5

If you're like me and don't like tornadoes coming STRAIGHT at you every-time, change the angle variance:
I:Storm_Tornado_aimAtPlayerAngleVariance=30