This address is also obsolete

Unless you are using the console, you can only create a new wallet that uses bch addresses in electrum new versions.
Not for individual vanity addresses like this. You simply create a new wallet, select "Import bitcoin addresses or private keys", and then paste the relevant private key with the prefix "p2wpkh-p2sh:" for a nested segwit address such as this one.
I agree that it is trivial... but I expected those basic features to be universal, and not something that only works in electrum and a few more wallets.
Well, there's more to it than that. Creating a universal signing scheme which will work for all bitcoin addresses and all script types is not trivial. If you are really interested, you can have a read of BIP322 and the issues surrounding it:
https://github.com/bitcoin/bips/blob/master/bip-0322.mediawikihttps://github.com/bitcoin/bips/pull/1347https://github.com/bitcoin/bitcoin/pull/16440Electrum have a created a very specific solution for signing with one specific type of address. And so if you want to use this specific solution, then just download Electrum.