I understand your problem , and also happens when you do a strength training, the tss does not correspond to the effort. Trainingpeasks is mainly created for endurance sports like triathlon , running and swimming and so, has some gaps. The better way to do it, is to rate your training as RPE ( RATED PERCEIVED EXERTION ), give a value of what you did from 1 to 10 per hour, see the correspondent value of tss and insert it mannually on your activity .
ex . first hour was a 7 , second hour was 5 … 7 is 80 tss + 5 is 60 = total value of training tss 140 )