Volume MuseSounds differs between different sections (eg. keys/brass)

I am currently working for a piece that features both brass and piano so I decided to download the MuseSounds sound library for 'brass' and 'keys'. When playing the project in it's current form (imported from mu3) the brass sounds -a lot- quieter and softer than the piano.

Of course, volume/dynamics between instruments differ, but a trumpet playing forte should sound at least as loud (if not more) as a piano also playing forte. Currently the brass section sounds like pianissimo in comparison to the piano.

Is there any easy way to fix this? Is this a bug? I'm more of a composer so I don't understand a lot of the mixer tab and don't just want to change things to get the sound right.

Thanks in advance for replying!