There is evidence that saurials can read the languages they know
In Dragon Magazine #292 (thanks to this answer for pointing me in this direction), it describes the lore and mechanics of saurials. Specifically, under each subrace, each has an Automatic Languages section, which reads (p. 41, taken from Finheads, since that's the kind of saurial that Dragonbait is, but it says the same thing for each subrace):
Automatic Languages: Draconic.
Bonus Languages: Common, Elven, Sylvan, and Celestial. Saurials have difficulty with other languages, and although they can understand and read all the bonus languages they know, they cannot speak them without spending skill points.
Since all saurials can apparently read the langauges they know, this would imply that Dragonbait would likely be able to at least read any languages he knows, even if he can't reply.
However, it also mentions that saurials can speak if they spend "skill points", which goes against the point of saurial's language somewhat, and even points out in a section specifically about Dragonbait (p. 43) that, although he initially lacked the ability to speak the languages of another race, he:
... learned to speak the Common tongue ...
which contradicts other sources about saurials generally (such as the information found in 2e from this answer).