As useful as Item Checklist is for 100% collectors, there are many items in each mod that aren't ever obtainable without Cheat Sheet or Hero's Mod. DBZ Mod's Trait system has debug items that force-give or remove traits and transformation levels, Thorium has multiple intentionally unobtainable items, like the Infinity Gauntlet, Redemption has spawners for its structures, and Fargo's Music Mod has unobtainable icons of the music boxes that it enables in the base mod, yet this mod counts all of them as obtainable items.

I really want to see some sort of blacklist function that lets players blacklist those items from the list, or even disable a mod from appearing in the checklist entirely. Ideally, it would be done in the UI, probably by shift/crtl/alt-clicking items to add to the blacklist. This removes them from contributing to the progress bars on the bottom of the checklist. If all items of a specific mod are blocked, that mod's bar disappears from the UI. Items can be un-blacklisted by toggling the filters.

If it can't be done that way, at least having something in the mod configs can be useful as well.