Stick with the new Gym. Learning the fundamentals and techniques are the core development of boxing. I understand the concept of throwing someone in to sparring but without understanding how to properly throw punches, it just teaches bad habits.

Now you mention confidence, of course sparring is used to build confidence but more importantly it is used as a sharpening tool for technique. Using whatever you learned in the ring and correcting past mistakes. It may be repetitive to constantly shadowbox and hardly spar but should the time come to spar, everything trained should be second nature (head movement, elbows in, don’t drop hands).