The fact that there are so many expats blowing up the cost of living doesn't help.
Enjoy it.
So far, there are no indications of the far-right gaining any amount of power with which they could govern. In a broader sense there have been a number of rightwing victories across Europe, but thus far Portugal (and Spain next door) don't look poised to join that trend.
Of course you are an American expat in Lisbon, so I assume you are living a life that's likely not very connected to local concerns. I assure you, Chega is growing like hell. I am not a supporter, I just see it.
Expats and the ballooning cost of housing is a part of it. The fact that you moved to Lisbon will have the victory of the far right here as a second order effect. Think about that.