What should happen is that the Timpani should be resampled as a velocity multi-sampled sound, at multiple velocities. This was a new feature added to Gold Soundbase 2. Any instrument with two different-shaded blue notes after it in the palette is velocity multi-sampled.
The software interpolates between the samples based on the velocity of each note.
In GOLD Base, "Timpani 2" isn't actually a multi-sampled (multi-layer) sound, but different filters are applied to the sound for soft and loud notes. If you play soft (low velocities) then loud (high velocities), it won't be the same result as if you increased the volume.
Please listen to the attached file. The first line is played with increasing velocities and no volume change, the second one with equal velocities and increasing volume.