Triggering from a keyboard is certainly possible. Question is, do you possess or wish to obtain the right type of gear to do it? The answer lies in a Sampler. To playback recorded samples of a human playing the harp. Loaded as a sample in the machine, then triggered by notes on the keyboard, can produce different tambres of the sound. Your recording process could record multiple takes of the human playing the harp to capture short "bounces" to moderate to long (I may not be accurately identifying the descriptive word for what we hear), which then in turn could be layered onto a single patch program. Meaning, that quick velocities trigger the short bouncing sounds, moderate for moderate, and slow velocities to trigger longer durations of the attack of the harp.
This would allow multiple samples to be triggered on any given note, distinguished by how quickly the note was struck, and then further variations by playing up and down the keyboard.
Then let's not forget all the various mouth positions that the harpist uses to bring about different nuances of sound. Those, too, need to be recorded and layered onto a keyboard patch.
Sampler is required.
Hardware-wise, Kurzweil K2500S (S must be in the model name), or K2600 (samplers became default equipment). Akai also made samplers as did Emu. I forget all the various brands and models.
Software-wise, you have lots of options, but then also need a good computer and soundcard so as to not have latency.