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hi, thanks

yes, qtractor does have audio input latency compensation, as far as it's reported by the JACK sub-system.

however, it might not be always perfect or precise, mostly depending on your specific soundcard device (USB is quite notoriously bad in this regard) and on the running JACK settings: as a rule of thumb, you should set JACK buffer-size to a bare minimum: 128 frames/period is good-enough for most purposes and prosumer-graded devices; for USB devices it's also highly recommended you're to set to a 48000 sample-rate, possibly on 3 periods/buffer.

if you can't run or start JACK reliably at that minimum sane specification, then you probably have one ugly and bad cheapo-graded device to begin with.; if you insist though, then abandon all hope on getting any real-time low-latency, precision multi-track recordings of any kind on qtractor... be that audio PCM or even MIDI:)...

when all's set and good(enough) as said above, you may need to adjust a few things and try on:

• qjackctl > Setup > Settings > Advanced > Latency I/O: add some systemic input latency (in frames) in the same amount you would possibly need to adjust, on any previously recorded audio clip in qtractor (not audacity);
• qtractor > View > Options... > MIDI > Playback > Queue timer (resolution) : make sure you select the high-resolution timer (hrtimer) or one with greater or equal resolution than 1000hz; also, try whether you get any acceptable results on keeping in time while recording MIDI, by enabling the MIDI queue time drift correction (or not).

hth.
cheers