@riot cannon minions are confusing, need clarification

TLDR; minion/turret changes in 6.22, 8.2 and 8.5 all conflict with each other

https://na.leagueoflegends.com/en/news/game-updates/patch/patch-622-notes

6.22 apparently made turrets deal a fixed ~14% to siege minions. Emphasis on apparently, fixed and ~ because:

• 8.5 revealed melee minions took 43% damage (increased to the 45% today), and on 6.22 patch notes it claimed to be ~45% at the time. This shows the values actually really aren't exact to an extent that matters for last hitting (as opposed to some minute decimals)

• 8.2 gave them anti-tower (heck the official term isn't even tower, its turret) socks in their inventory (as visual representations of minions passives for in game reference). This is two years after 6.22, making it newer. This shows that either there was some misinformation on the rioters who worked on this change (they didn't know about siege minions also taking fixed damage vs. turrets), miscommunication on the patch notes (siege minions don't actually take fixed damage vs. turrets) or the clarity wasn't really thought through (they have the passive listed like any other common passive, but it has no actual effect except in very niche situations).

• Melee minions and caster minions have gusto and phreakish gusto which tells us how much damage they take while siege minions don't have any gusto. Most confusing part: gusto said melees took 45%, which conflicts with 8.5 which said they took 43%. This means the rioters in charge of 8.2 didn't forget about 6.22 changes in general, but they weren't reading in game values and just did it by memory/approximation?

So do siege minions take fixed damage from turrets or not? Does MR/armour affect this? Does Janna E change damage to minions? Is the 14% before or after the turret damage reduction, or is it unaffected? Is it actually 14%?

I was gonna make a thread regarding when it's mathematically impossible to last hit cannons using most autos but I just don't know the actual numbers.