Some comments from @sipa in #12702.

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Yes, I think `importmulti` is superior in every way, except:
* Slightly less convenient to use (it requires redundant information, as you have to explicitly state what you want to import, and then give the keys/... to enable that).
* ~Doesn't support P2SH-P2WPKH yet~. Added in #14454

The latter can be fixed by just adding support for that case. The former can be improved by adding 'default' cases (e.g. if you prove a WIF private key, it can permit omitting the address, ...).

if(request.params[1].get_bool())
            filter = filter | ISMINE_WATCH_ONLY;
    UniValue entry(UniValue::VOBJ);
    auto it = pwallet->mapWallet.find(hash);
    if (it == pwallet->mapWallet.end()) {
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid or non-wallet transaction id");
    }
    const CWalletTx& wtx = it->second;
    CAmount nCredit = wtx.GetCredit(filter);
    CAmount nDebit = wtx.GetDebit(filter);
    CAmount nNet = nCredit - nDebit;
    CAmount nFee = (wtx.IsFromMe(filter) ? wtx.tx->GetValueOut() - nDebit : 0);
    entry.pushKV("amount", ValueFromAmount(nNet - nFee));
    if (wtx.IsFromMe(filter))
        entry.pushKV("fee", ValueFromAmount(nFee));
    WalletTxToJSON(wtx, entry);
    UniValue details(UniValue::VARR);
    ListTransactions(pwallet, wtx, 0, false, details, filter);
    entry.pushKV("details", details);
    std::string strHex = EncodeHexTx(*wtx.tx, RPCSerializationFlags());
    entry.pushKV("hex", strHex);
    return entry;
}
static UniValue abandontransaction(const JSONRPCRequest& request)
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }