Cardio and aerobic training are NOT the same, although many people mistakenly use them interchangeably. We all know that kettlebell training can be used to benefit the aerobic system, so there is no question there. Producing training adaptations for the heart (cardiac muscle) directly is not interchangeable with adaptations to the aerobic system.
For example, the most common protocol to increase the size of the left ventricle of the heart is 30-90 minutes of light continuous activity with the heart rate typically 120-150 BPM; this is commonly known as the "cardiac output method" of training. Keep in mind that athletes competing in endurance events like marathons or long cycling events will need MUCH longer duration than that.
This protocol is generally understood to work best when used with activities of little-to-no resistance, meaning it is hard to make a kettlebell work well for this protocol. One of the reasons for this is that achieving the desired stretching of the left ventricle of the heart is dependent on having sufficient blood flow into the ventricle, or "end-diastolic volume." If the heart is beating too fast then it doesn't have time to fill the ventricle sufficiently. Likewise, if there is too much resistance in the muscles, then the correlated vasoconstriction can result in reduced the blood flow back into the heart, again reducing the amount of stretch the ventricle gets.
This is why for the cardiac output method you typically need activities like walking, jogging, cycling, swimming, etc. for the method to work. The good news for you
@Kozushi as a judoka is that you can likely use uchikomi for this. If you did 30+ min of uchikomi at low-to-medium intensity levels that should be sufficient.