Spending $300 on an era toon should have netted a relic’d toon

The entire game is a massive waste of money. 

Out of curiosity, how did you land just g12 after spending $300? I spent nothing but crystals, and only two of my era units are g12 (even got a relic 2 Maul), and I'm pretty sure I could've gotten one of those two to also be relic 0 if I hadn't screwed up and made Barriss level 76.

All of my eras were 4 star and level 70 and I got g12.5 on all of them

I spent nothing, spent no crystals, had a month of at the start of the era; I was a month behind.  I watched one guide and learnt one small technique about the purge, for coliseum.....and all of mine are gear 12.

I'm not understanding some of the struggles.

You clearly don’t understand what you were spending on. You bought materials that were fully achievable free-to-play.  The benefit of this was higher placement in the Coliseum Leaderboard to get more Relic 10 or LST rewards. Yes, CG didn’t explain a lot but it wasn’t hard to figure out after 3 months.

For future reference, do not buy any of the materials for the purposes of getting gear levels if you do not plan on also spending on the Mk 7 or Mk 8.  If you only plan on level 70 or below, there is no spending required.  Only spend for the Leaderboard advantage.

Even level 75 is achievable on all 7 characters without spending anything on the Era materials so long as you got all the characters to 5-stars (with the 6th marquee character getting 5-stars on day 1).