How these worms transform my fruit production remains to be seen, but I can already see my mature Cherimoya going nuts on flowering, its self pollinating so I may have bountiful fruits this season.

Worms in garden is good! I spread some of this good compost to my veggie beds too! Fingers crossed.

Redworms (red wigglers; Eisenia fetida) are an epegeic species of earthworm found throughout North America and are certainly cold hardy to zone 6. AFAIK the eggs in their coccoons can sustain much lower temps than the adults. In the wild, adults control their temp by moving up, down, or horizontally in the soil to get away from harmful temps that become either too hot or too cold for them. Thus, they only need artificially controlled temp when colonized in a bin (because of that confinement).

I have a commercial worm compost bin, yet I've never purchased redworms for it. Instead I harvested the original colonizers of my bin from naturally wild redworms found in my own backyard. There was a fully shaded corner of the property under a canopy of towering old locust trees. In early July I simply began dumping fruit and vegetable wastes from the kitchen there, keeping out any gardening/landscape wastes. I did not disturb the pile until late October, when I found dozens of redworms near the bottom.
Most plants require some acidity in the soil, and wild redworms are adapted to acidic compost. Therefore colonizing your composter with wild redworms from your locale is far more advantageous for gardening than the use of commercially raised redworms that have become adapted to pH neutralized compost beds that are cultured for optimum production of redworms (not compost).

If your yard has no deep shade with litter from old growth trees, then it may not have any wild redworms regardless of which climate zone you live in. In that case, if there is a woodland near your neighborhood, then late next spring start a temporary compost pile of kitchen wastes at a secluded spot there for a few months. That should be sufficicient to amass a starter supply of wild redworms for your home composter.