“track down his estranged girlfriend” = goal
“recovering alcoholic” = protagonist character flaw
Now, “… poignant discovery into his past.”? Would you consider expanding …?

I think of a logline as a short story synopsis, rather than marketing. In essence, a logline contains the spoiler – marketing doesn’t.

If this were my logline, it might read:
When a recovering alcoholic [experiences an inciting incident], he must track down his estranged girlfriend [or suffer some terrible fate (insert story stakes here)], but when he learns of a poignant discovery from his past [state what that is exactly], he must [insert another story goal here], …

Of course, this is your story. What ’cause & effect’ (read: Inciting Incident) motivates our main character toward his story goal (i.e. recover lost girlfriend)? More importantly, what’s the character’s arc? Recovering alcoholic -> transforms into -> altruistic character …!
As a stereotype, alcoholics are usually selfish, self-centered, focusing only on their pain. Consider watching the film Leaving Las Vegas (1995). Slightly different premise, more a tragedy, because our main character never really learns, that love has always been with him – even in his dying (climatic) moments!

Good logline structure.

Audience is served one “socially inexperienced Papuan girl”, who experiences an inciting incident with one “young (male) recluse”. Love is the motivator driving this plot (and genre is Romance).

So, in the style of ‘When Harry Met Sally…'(1989), what then is eternally keeping these lovers apart? For Sally and Harry it was timing (each seemed to be in another relationship when ever their lives crossed). Or, think Shakespeare and his beloved Romeo and Juliet! Two warring factions tearing their community apart.

Here, in this story we are presented illness as the conflict, symbolized by Western medicine vs.native lore. Big idea, noble in spirit, but well, difficult to “visualize”.

My empathy reaches out to the fatally ill boy – yet it’s clear our Papuan girl is the protagonist … What must she “do” (think verb/action) in order to save her beloved (other than sit by his bedside and have a long philosophical argument about Western vs native medicine)?

Story may be aided by introducing a third “Villain” character. This character causes (deliberately or otherwise) the illness of the recluse boy, and my represent the antagonist of ‘native medicine’.