The update script runs /import on the downloaded file, i.e. it executes it — that is why it uses
check-certificate=yes-without-crl and never no. Bootstrapping the root over an unverified fetch is a one-time
trust-on-first-use step: compare the fingerprint before relying on it. On RouterOS 7.19+ check
/certificate settings print — if the built-in trust store is enabled for fetch, this step is unnecessary.