In designing ultra-efficient noise immune nanoscale circuits and systems, Schmitt triggers (STs) are vital components influencing total functionality. This article proposes an ultracompact ST using ferroelectric carbon nanotube field-effect transistors (Fe-CNTFETs) and a robust ST latch. By using the unique electrical futures of the Fe-CNTFETs, the proposed ST has been designed in a particular way to only employ two transistors similar to a conventional binary inverter. Moreover, by utilizing the negative capacitance feature of the Fe-CNTFETs, the proposed ST can perform the backup and restore operation during a scheduled power gating or a sudden power outage without imposing any additional transistors, interconnects, and control signals. The proposed ST latch is hardened to soft errors occurring due to unwanted single-event upsets (SEUs). Our extensive simulations demonstrate that our proposed ST latch offers lower transistors counts (on average 34%) and more energy savings (on average 79%). On the other hand, our design has shown 5.6 times on average higher critical charge tolerance than the previous counterparts due to its soft error hardening circuity and the superior hysteresis behavior of the proposed Fe-CNTFET-based ST. Moreover, the auto-nonvolatility of the proposed ST makes the proposed latches immune to the sudden power outage, which was not devised in the previous ST latches. Our results show new pathways in designing ultracompact and efficient nonvolatile ST latches using the Fe-CNTFET technology.