Learn Portuguese (Portugal): O maestro é que fez a orquestra acelerar o andamento. - The conductor was the one who made the orchestra accelerate the tempo.

This is the standard rule for causative verbs. When verbs like fazer (to make), deixar (to let), or mandar (to order) cause someone else to do something, the second verb stays in the infinitive. Here, fez shows who caused the action, and acelerar is the resulting action.

Could I put the two verbs together and say fez acelerar a orquestra?

Yes! With causative verbs, you have two options for word order. You can separate the verbs with the person or thing doing the action (fez a orquestra acelerar), or you can keep the verbs together (fez acelerar a orquestra). Both are perfectly natural in Portuguese.

Why does the sentence use the present tense é que when the main action happened in the past (fez)?

É que is a fixed emphatic phrase used to highlight a specific part of the sentence (here, the conductor). When used this way, it doesn't need to change to the past tense to match fez. You could actually remove it entirely (O maestro fez a orquestra...) and the sentence would mean the same thing, just with less emphasis on the conductor being the one who did it.

Does andamento always mean tempo?