The upstream SDK is currently updated several times a week: https://repo1.maven.org/maven2/com/adobe/aem/aem-sdk-api/. The latest release of io.wcm.maven.aem-cloud-dependencies is from 26th of September. It would be nice to outline in the readme at https://github.com/wcm-io/wcm-io-tooling-aem-cloud-dependencies/blob/develop/README.md what the (approximate) release cycle of io.wcm.maven.aem-cloud-dependencies is. In addition a Maven property would be nice which would allow to override the version from aem-sdk-api in https://github.com/wcm-io/wcm-io-tooling-aem-cloud-dependencies/blob/4be21e74713b49c11f8cc287115e8fc4d8527a6d/pom.xml#L83
i've added a notice to the README - we usually plan at least one updated release per month.
i think defining a separate property for the AEM SDK version will not work with "import" scope for the dependency POM, but it's easy to override the version by redefining the AEM SDK dependency in the downstream POMs with a newer version.