A catastrophic failure is very unlikely, but you may get spoke breakage after some time riding.
If I were you I would save my pennies until that day comes (if it ever does) and buy a new rear wheel (the front wheel is much less heavily loaded and generally you won't have an issue) with 32 spokes and a Shimano hub (I find Shimano hub bearings and overall construction to be the best).
Also, if the bike has 23mm wide tires, see if you can fit 25mm or thereabouts... this will allow you to run your tires at a slightly lower pressure which will then help transmit less shock through the rims and spokes and hubs.
Also, the 2014 Allegro 3.0 had 105 components, not Ultegra... so either you were misinformed or the previous owner upgraded the parts on it.