You can add a domain-level redirect e.g.
[[redirects]]
from = "https://wiki.asellus.org/"
to = "https://asellus.org/wiki/"
status = 301
force = true
I suspect (I have not tried) that adding a :splat (as below) may in turn negate the call from the proxy causing an infinite loop
[[redirects]]
from = "https://wiki.asellus.org/*"
to = "https://asellus.org/wiki/:splat"
status = 301
force = true
In this case I believe the proxy would get redirected back on itself and fail.
[Support Guide] Making redirects work for you - troubleshooting and debugging is a great resource for everything redirects related.