There are two bits in two consecutive sentences I don't fully understand. You will be pleased to learn that this post is 99.9% rant-free!
Pyrrhus was still fighting those pesky Romans. This is just after he'd beaten them is battle, so presumably he still thinks he has the upper hand.
Pyrrhus, cum adversus Rōmanōs parum prōfectūrum sē intellegeret, Siciliam diciōnis suae facere statuit. Inde rediēns cum Locrōs classe praeterveherētur, thesaurōs fānī Prōserpinae spoliāvit.
Pyrrhus, since/although/because he realised was about to set out too little/not enough against the Romans, decided to take Sicily by force of arms. Returning thence, while his fleet? was passing Locros, he robbed the treasure of the temple of Porserpina.
As you can see, I don't know quite how to translate parum prōfectūrum. I can't make sense of 'to be going to set out too little'. In the second sentence, I can't find Locros in any of my dictionaries, but I'm assuming it's a place? The cum goes with the subj. praetervehetetur, not the classe in abl. So why is classe ablative? Is it by means of his fleet? 'Returning thence he passed Locros by means of his fleet' doesn't really make sense to me.
Any help would be appreciated.