I think you grossly underestimate Ranji.
Yes there are a questionable pitches and you occasionally get to face pretty poor bowling but it's still an intensely competitive league especially at the Elite level.
Even if I concede that technique is not tested (which I do not) at the domestic level, at the very least, a high average establishes temperament and hunger for runs.
Obviously, the selectors do look for technique which is why the likes of Sarfaraz aren't getting in but it's not like we're so starved for backfoot technique high up the order that we're having to compromise so much on temperament. Jurel's technique is solid, Jagadeesan opens for TN and has been piling up the runs for a couple of seasons now. Yash Dubey opens for MP of late and of course Easwaran's been waiting.
Sudarshan does look stylish against pace but his technique against spin will always leave him vulnerable.