I applaud what you are trying to do and patterns will emerge but you are going a bit overboard.
1. You list 45 characters of "interest", way to many points to track/be useful for TB where you are trying to herd 50 cats. A lot of those are not even rare/difficult to get, pretty much characters in the GW or Cantina and even Arena Store should be common/covered, the hard node characters will most likely be the rarer ones. You also mention Hermit Yoda which I don't think has appeared in any platoon. Now obviously this is really situational depending on the veterancy of the players/guild, newer guilds will have more gaps...
2. Just a suggestion but your "format" is a bit complicated to get the data you want. Just ask for what was the highest #s you have seen for what character, what character. Which characters stopped you most from completing a platoon. Yes there is a pattern where toons are, Phase 5 had a whole bottom row of phoenix in the bottom territory but I think even though this is true still doesn't really change the fact at the end of the day there most likely will be enough randomization that you need to focus on coverage as stated is your original goal.
To answer your initial question of how many of a character was needed: I heard directly from shard/guild mates that the # can be up to 11 and even 12 times in a single phase. The 11 was Lobot, can't quite recall the 12. Though I directly saw 5-6 being common each phase for my guild.
Toons my guild ran into issues with (88m GP):
Wiggs: Wedge is just the strongest rebel lead, biggs is his partner. While you can generally get away with giving up biggs, wedge is more difficult just because his leadership is sooo good for TB.
Chaze: Mixed bag here, lots of people still don't have them complete but we did hear from guildies not wanting to give up their g7 Bazes. These are like wiggs, a critical combo.
Resistance: While these were not difficult for us last time around, they will soon be since they are sooo effective in later phases, more guildies will farm them and not want to give up their "wins"
New Ewoks: still p2p all paploo and logray were a auto no for us phase 5+
Falcon: duh, though we didn't see more than 1 in any given phase.
Phantom/Ghost/Gauntlet: at around 5-6 stars... These will drop from the list within a month or so since they are in fleet.
Kylo Shuttle/Reaper: just like ewoks but worse since impossible to farm beyond 3-4*