Quote from krYshuT »A copy of a spell or ability is itself a spell or ability, and behaves much like other spells and abilities (C.R. 707.10).
Curse of Predation
Weaver of Harmony
Oran-Rief Ooze with a +1/+1 counter on it
- I declare Oran-Rief Ooze as an attacker.
- Two abilities trigger at the SAME TIME, I put 4 counters on the Ooze. (one for its own trigger + Hardened Scales extra one, third one for Curse of Predation trigger + Hardened Scales extra one)
- I copy Hardened Scales' trigger with the Weaver
Hardened Scales doesn't have a trigger. It doesn't create anything to target. Weaver of Harmony can only target abilities of Curse of Predation, here.
Each triggered ability, or copy of a triggered ability, "would put one or more +1/+1 counters on a creature you control" at a different time, so, you get another +1/+1 counter for each one through Hardened Scales. If you actually do copy the Curse of Predation ability, you add six +1/+1 counters in all.
In Example 2, again, there is no ability put on the Stack to target from Hardened Scales. Beastcaller gets two counters, that makes Scourge get two counters, and that's the end of it.