Composite build with a dependency on a multimodule build

Consider the following project; build, settings
This project is a composite build for a main program and plugins for a system I created, which is also an includeBuild for this project (/libs/haruhi)
I have dependencies on multiple libraries, located in /libs/, but there’s one library I can’t work out the syntax for including, and this is /libs/sniffle. That project is a multimodule build of 4 plugins, with no home elsewhere, the root build should have access to. I can’t add each plugin as a composite build as some depend directly on others, unless my choice of syntax was just wrong which is highly likely
I’ve tried what was proposed in this question, however, I don’t understand deeper Gradle ideas to understand what I was doing wrong in my interpretation of it

If more information is needed, I can provide it upon request. Thanks for reading, I hope you can help

If you call the projects task on the sniffle build, you see there are the projects

Root project 'sniffle'
+--- Project ':discordrpc'
+--- Project ':pluginmanager'
+--- Project ':settingsgui'
\--- Project ':tipoftheday'

If you then call the :discordrpc:outgoingVariants task on the sniffle build, you see in the outgoing variants:

    - sniffle:discordrpc:unspecified (default capability)

So what you want is for example implementation("sniffle:discordrpc").