For the record, the gigantic titles trend started on Japanese Webnovels for a very simple reason.
Syosetu (the site where they publish their webnovels) doesn't have covers in it.
Without covers, the only option you have available to pull the attention of readers is the title. Nobody will read your synopsis if your title/cover doesn't pull their attention, and Syosetu doesn't have the cover option, so the authors have to rely on the title alone.
That's basically the origin of the trend and how it started... Then those webnovels started getting translated and some people became fond of them.
Then, when writing their own webnovels, people were inspired in the webnovels they liked and started making longer titles too, which leads to longer webnovel titles appearing on western novels too, even though they aren't necessary here.
That's basically the gist of it.
As for how effective it is as a marketing tool within Scribblehub... I think it's neutral. I don't think long titles draw more or less attention than short titles... Shorter titles tend to feel more professional, but longer titles have their fans, so I think it evens out in the end.
So, just do what you prefer, really.