HI ive only had a teaspoon of leachate in over 4 months so I reckon your wormery must be too wet.
Can you move it to be under cover? Or add more shredded paper to bulk up the contents?
Mine has been getting too dry & ive been having to gently water it to keep the shredded paper & newspaper damp.
When I set it up I was advised to put a brick with an central dip in the bottom so any worms that fall through can get up out of the water, maybe this will help prevent more worms drowning.
The tiny flies may be fruit flies. If you cover the scraps of food you add with a layer of damp shredded newspaper (about an inch or so thick) it stops flies from settling in.