Galaxy instance is pretty much defined by its tools and those differ from Galaxy to Galaxy. See https://wiki.galaxyproject.org/PublicGalaxyServers for the list of public Galaxies - they would often have very different glossaries. Moreover sometimes tools are not consistent with their term usage even within the same domain. I think your approach with searching for the term is alright. Often the best documentation is offered by the homepage of the tool itself or the paper that is often cited in the bottom of the tool form.