Can you still progress or at least maintain performance if train only 2x a week for a few months?

Given you've only started 4 months ago, and train 3-4x a week.

Yes I think you can not only maintain your current performances but also improve them if you train correctly. Obviously it won't be as efficient as if you train more.

But because you're still a beginner, it should work.

It wouldn't be the same if you're someone who is already at or near peak level and train 6-7 days a week.

Adaptation requires changes in the quantity of enzymes. Those enzymes don't stay around forever. They reduce in number after a day or two, depending. Any ramping up of enzyme numbers will fade back down to where you were, unless you re-stimulate the process with frequent easy runs. Walking won't suffice. It has to be the actual running muscle fibers. The trick is to run as trequently and fast as you can, without creating damage. Some enzyme changes can last weeks, some have half lives of 20 hours. Those short lived molecules will not be produced enough to enable advancement in your training, unless you run at least 3 times a week, maybe 4 times. It is hard to get data about half lives of enzymes and substrates involved in running. And, the molecular adaptations are still primitively modeled. So, no matter how much we know, its still a drop in the bucket.