Pretty easy AS all things considered. It is an ult refill one, so Cyrene teams will be overwhelmingly powerful especially with Anaxa and Mydei. Sparxiecon boss is still kind of a brick against Bounce units just like in the beta, so your Welt can vary around 200 AV depending on Bounce RNG (had some really bad Bounce RNG here, would be a 1600+ clear if i got good RNG). Also, double DDD + Wind sets here would probably be much better due to the ult refill, but i used Sparkle/Sunday's respective sigs and double Sacerdos instead cause i didn't wanna bother.
Second side has terrible buffs for Welt (DoT, Erudition, 3x Remembrance requirement) so i wouldn't use him there even though theoretically the teams i used have better matchups if swapped around. Might be worth trying though.