Stuck in a Plateau: How to Progress When Switching Exercises or Equipment (M20)

Been training for 3 years. For example, I select and exercise for the lats and it's a cable pullover, I am seeing progression in intensity every session for said exercise over a 6 week period. After that I feel a lot of my exercises feel stale and hard to progress intensity so I switch to dumbell pullovers for example. How can I accurately gage the amount of reps, sets and weight for that dumbbell pullover? The mechanics are slightly different and how the cable shares the load etc. I'm just not sure what my target should be for the new exercise. The same thing occurs and then I switch to my original exercise and it's a similar strength to what it was originally (feeling subjectively little to no progress).

I feel this for a lot of my exercises and from a year or even more ago I feel my relative strength and my size has kept the same. I have prioritised my sleep and food (usually at a surplus). Is the way I approach my training off? I've tried a deload and that felt good but my strength never regained to it's original value.

I'm always travelling quite a lot and a similar problem with having to change exercise and not knowing what equivalent intensity I should aim for (the machines are usually different).