Does Hard Bargain countering a spell on Abandon Hall still allow that spell to count as played for the buff?

No, if a spell is countered by Hard Bargain while your unit is on Abandoned Hall, that spell does not count as having been "played," and your unit will not receive the buff.

According to Rule 425.1.b, a card that is countered is not considered to have been played. Because Abandoned Hall requires a spell to have successfully completed its resolution process to meet its trigger condition, a countered spell fails to trigger the ability.

The sequence of events:

1. Initial State: You play a spell. This spell enters the chain.
2. Reaction: Your opponent plays Hard Bargain (or another counter) targeting your spell.
3. Chain Resolution: The Hard Bargain resolves first (LIFO). It counters your spell, which is immediately cleared from the chain and removed from the game process.
4. Outcome: Because your spell was countered, it never finished its resolution process. Therefore, it is not considered "played," and the triggered ability on Abandoned Hall never enters the chain.

This interaction is confirmed by multiple RiftJudge FAQs (including #10825, #10646, #10782, and #11222), which consistently state that countering a spell negates any "when you play a spell" trigger conditions.