Power for bouldering will come back super fast, and you’ll probably be lighter with stronger finger tendons and core muscles after some sport climbing. I have a friend who didn’t climb at all for six months due to a split shoulder and she quickly worked her way to being stronger than prior to injury in like 2-3 months, she sent an indoor v6 a few weeks ago and had never done that. Read Steve’s blog article about myelination, a big chunk of strength comes from the brain and you never really lose that.
I really love bouldering and resort snowboarding, and in may I’m going to ditch both these activities (gonna splitboard a bunch next winter for sure though) to get serious about alpine trad climbing. I am confident that chasing grades will be much easier after a bunch of big hikes and easier multipitches the day I feel like sportier climbing will bring me more satisfaction upon success.
Also, you might want to consider forums like reddit’s climbharder for sport climbing, as well as sources of training information that pertain more to shorter duration effort. When people on this forum climb it’s usually after crossing a bergschrund or for several hours. Going from v6 to 5.12 on bolts you wont have the same training needs as someone who wants to climb cracks in alpine environments.