Many things are a matter of perception and experience. Most good mechanics. Or a friend that has more automotive experience than yourself might give an opinion in person.

Since it seems to have been coincidental with the injection pump change and rear transmission seal change is a strong issue. Neither am I familiar with your car. Did you drop the back of the transmission lower to change the seal?

Also since you primed up the chain tensioner is it too tight if that is possible? Yours would have the one way ratchet advance I would think. Again I do not know if an individual could overtension it manually.

Without hearing it personally can make it harder. Did you take the chain tensioner apart and reinsert from the back? If not you may have accidentally gotten past where it was originally running. The chain tensioner did seem normal to you?

Again I am not even sure that is possible. Sorry that I do not have a eurka for you although it is possible some other member with far more experience will..