This would allow wallet operations like funding transactions with smart contract-based inputs such as LN, or any input the Core wallet doesn't know how to sign for.

https://github.com/bitcoin/bitcoin/pull/17211#issuecomment-933674310
if (nSmartTime <= latestTolerated) {
                        latestEntry = nSmartTime;
                        if (nSmartTime > latestNow) {
                            latestNow = nSmartTime;
                        }
                        break;
                    }
                }
                nTimeSmart = std::max(latestEntry, std::min(blocktime, latestNow));
            }
        } else {
            WaetLogPrintf("%s: found %s in block %s not in index\n", __func__, wtx.GetHash().ToString(), block_hash->ToString());
        }
    }
    return nTimeSmart;
}
bool CWaet::SetAddressUsed(WaetBatch& batch, const CTxDestination& dest, bool used)
{
    const std::string key{"used"};
    if (std::get_if<CNoDestination>(&dest))
        return false;
    if (!used) {
        if (auto* data = util::FindKey(m_address_book, dest)) data->destdata.erase(key);
        return batch.EraseDestData(EncodeDestination(dest), key);
    }
    const std::string value{"1"};
    m_address_book[dest].destdata.insert(std::make_pair(key, value));
    return batch.WriteDestData(EncodeDestination(dest), key, value);
}
void CWaet::LoadDestData(const CTxDestination &dest, const std::string &key, const std::string &value)