I'm not sure I like the idea of the Yehat bioengineering some dumb dogs into intelligent, spacefaring Shofixti. Why go through the trouble? Why not bioengineer something new or smarter? Besides, the Ultronomicon says the two species respected each others' way of life before the Shofixti were uplifted, and it was like feudal Japan (but with mud huts).
I'd prefer to think they were intelligent, but didn't have the lifespan or environment that permitted rapid gain in knowledge. After all, Tanaka looks pretty old and thrashed in his scout, and that was 20 years after the war. If he was an older man 20 years after the war, after his prime, then surely he has a short lifetime. The Shofixti are also viable crew after a very short time, so clearly the Shofixti are also old and mature in just a few months. Maybe his prime was at age 2 (or other single digits), and they simply live short lives. If that is the case, if they only get to be 30 or 50 or so, then maybe learning higher education could be harder for them with their shorter lifetimes, and thus they were further behind.
Of course, there is also the possibility that they're actually a younger race than us, with their oldest ancestors only a hundred thousand or less years old (Humans, as of now, have direct ancestors traced back several million years ago). They may, in fact, progress faster than us, but have simply started much later. Their 'uplifting' may have been like what the Europeans did to/for the Native Americans, giving them an understanding of their culture, integrating them in (but with more cooperation due to respect/trust), and teaching them about modern technology. There are only 50 years between the Yehat finding and uplifting the Shofixti and the conflict in SCI. That's a short amount of time to go from swords to lasers, and they seem to have a decent understanding of space technology.