In order to avoid either writing yourself the full ID or searching the right ID bewteen all the ones available, it can be really useful to tab-complete only a portion of the ID. This is especially true for scoreboard criterias, so this is what my example will be on, but IDs could need that as well :

What would be expected (and how it works in 1.12, at least from what I remember, but at worst there's the idea) :

• Write / paste : /scoreboard objectives add obj

• Type "m" then press Tab → "minecraft."

• Type "m" then press Tab → "minecraft.mined:"

• Type "m" then press Tab → "minecraft.mined:minecraft."

• Type "pot" then press Tab → "minecraft.mined:minecraft.potatoes"

What actually happens :

• Write / paste : /scoreboard objectives add obj

• Type "m" then press Tab → "minecraft.broken:minecraft.acacia_boat" (so if you want to target potatoes, you will have to keep pressing Tab / down arrow for an hour or so OR write everything by hand, at least until you get to "minecraft.mined:minecraft.pot")

Also, I can't remember if something like that was there in 1.12, but a useful thing would be to have additionnal suggestions that would always be at the top (except if there are results that would end before having a "non-letter character") but that would never suggest anything after the next "non-letter character".

Explanation :

• Start with nothing written for the criteria → Every ID is suggested

• Type "d". Let's imagine you have a mod called "Doors" → Suggestions will be "deathCount", then "dummy", THEN "doors" items

• Delete that "d", you actually wanted to type "minecraft" → Suggestions are "minecraft.", then all the full IDs starting by that

• Add that dot → Suggestions are "minecraft.broken:", "minecraft.crafted:", "minecraft.custom:" etc (so we have a clear list of what is possible directly after "minecraft.", instead of having to scroll down for half a day or try every letter, and more than carefully since something like "crafted" and "custom" happens), and then we have all the full IDs starting by that

• Tpye "c" → Suggestions are "minecraft.crafted:" and "minecraft.custom:", then all the full IDs starting by that (as usual)

► So, in short, nothing changes at all about which full IDs are shown, we only add what are all the categories in which they are scattered.