From the FB group Building Transistor Radios
Regenerative / reflex designs are not as stable as superheterodyne radios. One problem is the design depends on factors that are not predictable such as gain and feedback, which are not linear. The regenerative reflex depends on the circuit being on the verge of oscillation, which is not linear.
I’m not saying that the circuit cannot be stable. But the manufacturers built thousands of them with parts that were made especially for the circuit. If you were to do the same thing, you would get good results. But I assume that the average hobbyist doesn’t have the ability to do this.
I have built several of the regenerative receivers and I’ve had poor results with all of them.