If you spawn a Wolf with spawn event Minecraft:become_angry it does not spawn the Wolf as aggressive one, while i think it should cause the Wolf to attack the player immediately after being spawned when player is in survival or adventure mode. In fact, this spawn event does not do anything while it's mentioned on dig Minecraft spawn events list and the spawn event is said to have Been added in v. 1.12. This all stems from my personal experiments and experience and made it harder for me to complete my map projects.

Report goal: make the spawn event Minecraft:become_angry to cause the Wolf  to be aggressive to all players immediately after spawning and until run-away or forever. It could be useful mainly for content creators.