Talk about a leap of faith!
No, the tentative language clearly indicates that this is *not* a "leap of faith", it's a careful indication of the preliminary nature of the models.
A "leap of faith" *would* have been a valid charge if they had simply declared their conclusions in declarative language like "...is due to...", etc. -- but they did not do that.
Like any preliminary scientific finding, they're careful not to overstate the amount of certainty. And also like all scientific proposal, no one experiment, model, or paper can (nor should) instantly establish the idea beyond question. "New" ideas are always presented tentatively, no matter how well they are supported by experiment or evidence.
Only after they have been put out into the arena of scientific verification (via peer review, replication, etc.) and have withstood all objections that could be raised to them, and successfully predict new findings, well enough to achieve widespread acceptance in the scientific community (and do so better than current or opposing theories), will the new ideas reach the point where they can be reasonably written in language that implies a good degree of confidence in its trustworthiness.