I don't know if "correct" is the proper word here but  as far as I can tell it is the accepted  or expected output. I find many of the waveform generators in Csound do not produce textbook looking waveforms - the squares are not square and, like the saws, are either concave or convex in places etc. Corners often show added harmonics similiar to waveforms run thru filters with resonance. 

Of course there are many oscillator opcodes so I do not have much knowledge where they stand in comparison. 

The sine waves it produces are fine, it seems the more harmonically rich waveforms are not quite as one expects to see. I have my own theories as to why (tables etc) but am not knowledgeable enough to know. 

Perhaps others will chime in or correct me.

Personally I just accept this and use Csound for what benefits it does offer like granular synthesis, convolution, randomization of parameters and lots of other nice features

If you're looking to work with more traditionally "pure" or even some crazy and interesting waveforms you can always use the diskin or soundin features to load your own samples or single cycle waveforms

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