I was a gym bro before I discovered mountain sports and balancing my gym habits with my mountain performance goals has been a long time struggle for me as well.
A template training plan is a road map to an event based peak performance of an objective. The 22 week mountaineering plan is designed for multi day expeditionary mountain objectives and exists in a vacuum that assumes you have no other goal. Mixing in other elements/training goals is counter productive, a recipe for sh*t stew at the end of the day.
I found it helpful to look at the different components of training like pots on a stove. Having more than one pot on full boil at the same time can quickly lead to chaos. For best results, it is best to choose your focus and put the pots on simmer.
If you are just going hiking on the weekend / not doing an expeditionary mountain objective and hypertrophy is the goal, I would focus on hypertrophy and just pack in as much easy cardio/hiking as possible for days out in the mountains. A lot of people I go to the mountains with just go hiking on the weekends. They aren’t going to set a record/win a race but they do just fine.
Also I just got back to lifting after a two years of doing mostly running and doing body weight stuff due to the gym being closed because of the pandemic and I haven’t lost any muscle… Losing “my gains” would really help my running/climbing goals but nothing I do seems to work. Long story short is everything will be ok if you take a break from hypertrophy for 6 months to focus on mountaineering training. I totally get the sentiment of your post tho, kicking my old gym habits was a struggle for sure.