After the second time, I noticed that one of the speaker cables’ spades was broken
This I think is your problem. Tube amps do not like to be run into an open circuit. If your spade broke and this opened the circuit that could do serious damage to your amp. Then again could be a red herring. You didn't mention the sound cutting out at all like it would do if the connection broke, and we don't know what you mean by "broke". My guess would be that it cracked, but not enough to cut out completely just enough to make it sound bad and at the same time create an unstable load the amplifier couldn't handle, causing it to blow a fuse.
The Artesania thing is probably a misleading detail. Your amp has a lot of venting but the Artesania isn't anywhere near large enough to interfere with that, at least not the one I found on-line.
It could also be that this is all coincidental, and it just happens that a tube decided to go bad at the same time as a spade broke and you are trying out a new tweak.
There are also resistors under the tubes and if you burned one of those out for any reason the amp won't run and will only blow fuses until those resistors are replaced.