I love your spreadsheet. swgoh.gg is better for this purpose, but I still love it. The number of spreadsheets I've created for this game is a little insane, but I find them very fun. And yours is colorful, so it's even better.
OK, let's talk about game basics. No matter what toons you go for, you need credits to develop them, and eventually you're going to need zeta mats to finish off their abilities. Maxing out Credit Heist will be important to your growth. You need 5 Scoundrels at 5* (at least). Boba is in good shape. You should do STHan because he's needed for CLS. Chewie is already at 4*, so take him up to 5* and leave him there. The other two are up to you - I went with Lando and Cad because I was getting STHan from Squad Arena and those two didn't conflict. Dengar would be another good option if you're getting a steady supply of guild store credits; Bounty Hunters are getting a rework and I bet he'll be a useful toon in the near future.
Zeta mats can be gotten through ship challenges starting at level 78. You're a bit behind to hit that target, but you should still start working on it. You'll need 5 DS ships at 4* to get Executrix to 5*, then you'll need 8 ships (any side) at 5* to do the mat challenge. The nice thing about working on DS ships is how many overlap with a good Empire team, and you need an Empire team for R2-D2. Vader, Tarkin, and TFP are all toons/ships you should work on. Vader's ship is a slow farm though, so FOTP, Geo Soldier, and SF (FE)*** are all other possible options. Boba's ship is also a slow farm but quite useful. You already have TIE Silencer at 4*. Definitely finish Biggs; his taunt on Target Lock is a big help on winning challenges.
***I hope the abbreviations come across between English and Spanish!
Galactic War... I do agree you need to finish this for the rewards, and I think if you develop a Scoundrel squad and an Empire squad with decent mods you might get through it. I don't know if there's time for you to get 5 Rebels to 5* before Palpatine comes around again, but his leadership on an Empire team plus Shock and Stun abilities help a lot with GW. In fact, do the math and see if you can have 5 Rebels at 5* by May 10 (just a guess that he will come back around that time, but I think it's a good guess) - this might be a good investment for you. You need Old Ben, Leia, Luke, and STHan for CLS anyway so it's not wasted farming.
It's not a top 200 team, but Vader, Tarkin, TFP, KRU, and Boba might get you up a tier in Arena. Biggs is a good toon, but he's not as effective without Wedge. Healers don't stay effective in Arena for very long.
Now, if what you REALLY want is to have CLS or Thrawn or Palpatine or some other specific event toon, my advice would still be to finish Scoundrels for Credit Heist but focus less on zeta mats and more on the toons you need to get that toon.
Does this help?
