That's great to hear!
I do have a Discord I just made public that you can join at https://discord.gg/eWkxcBHSy3
Magic spells in general do not give bonus dice. Though there are feats, magic items, pushing oneself, assisting, and devils bargains can give bonus dice. (I'll be working on magic items soon to help on that front.)
Magic in general follows the fiction on what kind of bonuses, if any, one may get. For the fireball example, if the bugbears happen to be close to each other it would make sense for the fireball casted to have improved effect and if the wizard has distance from them possibly improved position. (Though if the bugbears have an amulet of fire resistance the effect may be reduced.)
Hopefully that helps some. Feel free to join the Discord to talk about the minutia and ask questions!