The CMR Convention allows one year to bring actions arising from the carriage, and three years where there is wilful misconduct or a default the court’s law treats as equivalent (art. 32). Once it runs out, the claim is extinguished even if the damage is documented.
Do not confuse limitation with reservations: the art. 30 reservations (at delivery, 7 days, 21 days) preserve the right to claim; the art. 32 limitation fixes how long you have to sue. A written claim to the carrier suspends the period until the carrier rejects it in writing.