as it is now the random mod target is a huge pain to work with... frustrating even, on items with all 6 mods...
its actually far more efficient to start from scratch and craft white items, reload game to get a desired effect, save then use hell ingots to get those to a desirable level, then repeat the process and only suffer on the last few mods.....

can even make targeting specific mods cost another ingot or hell notes
and feed them ingots/notes to reduce the chances of hitting lower rolls.

(there is also not currently a way to re roll items base values, exa block chance, base dmg, absorb etc. which means crafting from black white items is that much more desireable)

(its also worth noting the frustration of reroll afix with new values landing on the exact same value being infuriating)