It doesn't sound like you were confused about whether they were the same project, it sounds like you were immediately concerned whether the other endeavor was in conflict with your trademark. That may constitute confusion but it's not the sort of confusion trademarks were designed to mitigate.

> the names of all Apache® projects, software products, and their logos are trademarks owned by the Apache Software Foundation on behalf of our project communities. Note that while some Apache project names and logos are registered in the US and various countries, even unregistered names and logos are still trademarks of the ASF and should be treated with respect.

Only trademarks registered with various legal jurisdictions are enforceable, such as the "Apache TinkerPop Gremlin" name you registered. Unregistered marks used by an Apache project are simply claims on the mark, which in many cases are not enforceable. One example is the Apache Groovy project, where its PMC members erroneously claim the exclusive use of "Groovy" for their programming language, when in fact their only valid claim is to "Apache Groovy" (and its previous monikers "org.codehaus.groovy" and "Codehaus Groovy").