1. Snow falls too fast.
2. Rain Particles are quite sparse. maybe make it show less particles when particles are set to decreased/minimal.
3. sometimes the particles are not appearing correctly on borders
4. the weather still appears over the particles.
5. there are no rain sounds

for snow yea i can see that for rain its more for performance reasons (i might add a cloth config thingy to increase the amount)
also pardon but im not quite sure what you mean by "borders" but if you mean like the weather "leaking" into other biomes thats intentional idk it just adds a nice "transition effect" also uh im not sure what the problem is with your rain sounds they work fine for me, and for the weather appearing over the normal particles yea i may have forgotten to reimplement the part that removes those visuals and have a fix up on github (curseforge soon) also sorry this is my first mod so yknow ye

If the visual problem still persists let me know after you make sure its not a resource pack conflict (as the way i fixed it is related)