I'm currently implementing changes to how titles are render in notifications. I was wondering why it was decided to truncate titles inside of notifications. I'm thinking about removing the feature because it would make it easier to implement making the page names inside notifications links. Showing the full page name is also critical to distinguishing similar-named named pages, particularly Wikibase entities which can often be similarly-named.
Topic on Extension talk:Echo
I think truncating titles was a trade off for having longer and more explicit notification text while keeping the whole text not too long.
Back around 2015, notifications used to have links in their text but it was removed in favor of the entire notification being a single primary link with a number of secondary links below and under the "..." menu. This was considered more usable, especially on mobile, by the designers at the time.
I have no opinion about your task specifically, I just wanted to share historical perspective.