org-mode allows multi-line titles, for example:

#+title: Spatiotemporal Variance-Guided Filtering:
#+title: Real-Time Reconstruction for Path-Traced Global Illumination

This helps with legibility. When exporting, org joins the multiple lines with a space as separator to produce the final title for the exported document.

Until now this functionality does not seem to be supported by org-roam. Only the first line will be used as the title.

I have to admit, I am not a elisp expert but I managed to narrow the problem down to the org-roam-db--file-title (thanks to its very hepful docstring!).

(defun org-roam-db--file-title ()
  "In current Org buffer, get the title.
If there is no title, return the file name relative to
`org-roam-directory'."
  (org-link-display-format
   (or (cadr (assoc "TITLE" (org-collect-keywords '("title"))))
       (file-name-sans-extension (file-relative-name
                                  (buffer-file-name (buffer-base-buffer))
                                  org-roam-directory)))))

I found out that (assoc "TITLE" (org-collect-keywords '("title"))) returns a list of the title lines. When joined via string-join it was consistent with default org behaviour. I also found out string-join was part of subr-x (so it might not be available by default?) but I noticed it was already used in org-roam.el, so this shouldn't bring in new dependencies.

However, I can't gurantee that other parts of the code have to be touched to accomodate this change, maybe someone with more experience with the org-roam code base could take a look at this?