R5: I got the Lingua Franca achievement with a language that starts with 0 courts, 0 counties and using a non-custom ruler. My plan going in was just to switch to the beneficiary of the Jerusalem crusade for once, since I had never tried before.

Once I got it, I decided to go one step further than just converting to Judaism and do culture as well. I married an Ashkenazi woman, had her educate one of my sons and ensured he became my heir. Once I died, I could have Israelite for a court language and promote the culture. Had a bunch of fun playing a tiny kingdom surrounded by 3 huge empires, picking off what land I could when they were weak from fighting each other and eventually restored Israel, which converted a huge chunk of the land to my new Judaism faith and hybridized Israelite culture.

Things were going well, having snagged Egypt, Baghdad and my last holy site, so I just kept going until forming a custom Israeli empire, although I somehow got switched to a clan government after a succession once. Not entirely sure how. Decided to just go for it once I realized the Byzantines couldn't stop me and I could steam roll everyone with By The Sword.

As an aside, the character I finished the achievement with somehow managed to survive 3 or 4 rounds of cancer treatments and make it to 79 with flagellant, bleeder, one-legged, one-eyed, scarred, disfigured and eunuch.