I agree to OP. The concept of world tension seems to be abusable. We have seen in the Japan WWW, that annexing China raises world tension to a level where no further actions from german side are needed for the Allies to guarantee, and, if extrapolated, even enter a war directly. Just assume Japan keeps expanding, world tension will very fast go up to 80% and more.
We did not hear a lot about this issue of "who" creates the tension. If it is an integer, then no, it will not help Germany avoiding early Allie-actions, since, as
@R1ob7 stated,
some world tension will come from Germany even in conservative approaches. And though the general concept of world tension seems appealing, I can't find why Britain and France would take less sh.. enanegans from germany if Japan annexes China, which is what it implies and explicitly does.
This may all be issue to balancing, maybe annexing China should not be a 40% hit on world tension, and if it can be balanced, it's okay for release, I guess. But the basic issue persists. When I think about it, I always come to national tension levels, which is Threat as we know it from HoI3 or aggressive expansion from EU4. But this was obviously scuffled for a reason in HoI4. But anyway, if world tension (and that's how I perceived it) needs to reach a threshold for any democracy to guarantee anyone against anyone, so if it just enables a diplomatic option, without target restraints, you'd better hurry as Germany.
However, in singleplayer, this might not be an issue, if AI sticks to roughly historical actions. And while it seems abusable in MP, MP is never historical, so you might end with France and Germany against Italy or what else.