Learn Portuguese (Portugal): Há muito tráfego ali, mas já reporto o problema. - There is a lot of traffic over there, but I will report the problem right away.

This is the pragmatic future use of já. By combining já (which usually means "already" or "now") with a present tense verb, you express an immediate or guaranteed future action. It conveys a strong sense of reassurance, like saying "I am on it" or "I will do it right this second."

Could I say já vou reportar instead of já reporto?

Yes, já vou reportar is perfectly natural and also means you will do it right away. However, using just já plus the present simple (já reporto) is slightly punchier and extremely idiomatic in Portugal for immediate, decisive actions.

I usually hear trânsito for "traffic". Why is tráfego used here, and are they interchangeable?

They are often interchangeable when talking about vehicles on a road, but they have different nuances. Trânsito is the standard, everyday word for street traffic or a traffic jam. Tráfego is slightly more formal and often refers to the flow or volume of movement, such as air traffic, web traffic, or heavy goods vehicles.

Why use ali instead of lá for "over there"?

Ali implies a specific location that is physically visible but slightly distant from both the speaker and listener. If the traffic were much further away, completely out of sight, or in a broadly defined area like another city, lá would be the better choice.