Hi,
I have reached a (non-preferred) solution. I modified the source code in /usr/lib/python3/dist-packages/lava_dispatcher/actions/boot/__init__.py under the http if section (approx. line 717 onwards) to have actual character delay instead of using the class property character_delay (which when I looked for it on git online it was simply 0). I also split up the download command I submitted through the test job as I had quite a unique one due to the circumstances explained already.
If anyone has suggestions that don't require me to modify the code, please let me know here. Otherwise, feel free to ask questions for particulars (not that I can be of much use, I just experimented heavily despite my inexperience with LAVA).
Best regards, Michael