Improve my SAT 1 score or do SAT 2 tests?
Should I focus on improving my 1420 in SAT 1 or do SAT subject tests instead? How important are the SAT subject tests?
It really depends on what school you are applying to.
If the school you are applying to has a 50% middle range of 1500-1570, then you should try to improve your 1420 to at least a 1440 but aiming for 1500.
If the school you are applying to has a 50^ middle range of 1400-1500, then you are good to go and I recommend you work on the SAT 2 subject tests.
CV feels that this cycle as long as you are within 60 pts of the lower bound of the middle 50%, you should submit your scores.
Keep in mind that 400+ schools have made both the ACT and SAT test optional with a few going Test Blind (won't even look at them if you submit) As a subset of the SAT suite, I would say the SAT 2s are even less required than previous years. Some schools like MIT have changed their policy to making SAT 2s Test-Blind, so they will not consider them in your application review.
If you have both strong grades, strong course rigor, and have done well on APs like getting mostly 4s and 5s, I would not worry too much about SAT 2s this admissions cycle.
Best of luck in your college admissions process.