Maybe try the searxng matrix support chat, I think there might be a few developers around that could point you in right direction:
https://matrix.to/#/#searxng:matrix.org
They also have a Mirc support channel is that is more your cup of tea.
I would try to find something a bit newer. Core 2 Duos are really power hungry. Find one with an i5 processor and a T at the end of the number, like i5 3450T or something. This will be a little less performant but run at 30 watt max compared to the core 2 duos 150 watt. Fujitsu esprimo are also a good cheap option and both lenovo and Fujitsu offer rather tiny pcs that work excellent for severs.
There is no need fire up a dedicated machine to do this. Use your router/ap running openwrt and connect a hdd via usb. The machine needs at least 128 Mb RAM (256 mb would be better). Install the transmission package, set it up, add a gig of swap space on the hdd and you are good to go. The AP runs 24/7 anyways so there will be very few extra power consumption. Vpns often don’t allow port forwarding (mullvad has stopped support recently if I remember correctly). You can just be a passive node and not often ports, that should work good enough. Consider seeding parts of sci-hub. it’s a project worth supporting imho.
You can just download once of the parts below with less than 12 seeds and set it to host without ratio:
https://phillm.net/torrent-health-frontend/stats-filtered-table.php?propname[]=seeders&comp[]=<&value[]=12&propname[]=type&comp[]===&value[]=scimag