I watched the video ... the one where he does not tin the stranded copper wire. Tinning the stranded copper wire is a bad idea. It will loosen. Even if you tighten it again, it will loosen. The solder flows very slowly under pressure, even with a lot of pressure. It is best just not to tin the ends where the screws are coming down .... so yes, my suggestion how to make it better = Follow the instructions in the video where they do not tin the wires. Ignore advice to tin wires that will be compressed with screws. I understand you said you prefer to solder them in place, but you keep trying to justify tinning the ends when they are screwed down.
w.r.t. AC, way back early in my career I did a short stints in industrial electronics and got to see the end results a few times of someone tinning the ends of wires, right up to melted terminal blocks.
This is a well known issue, and unfortunately you can find a thousand threads on the web discussing it and a thousand wrong recommendations. In any environment with properly trained staff (not to mention say a UL inspection) it will never be accepted.
https://cdn.thomasnet.com/ccp/00142951/263810.pdf
https://www.eptac.com/ask/when-to-tin-and-not-tin-wires/
w.r.t. AC, way back early in my career I did a short stints in industrial electronics and got to see the end results a few times of someone tinning the ends of wires, right up to melted terminal blocks.
This is a well known issue, and unfortunately you can find a thousand threads on the web discussing it and a thousand wrong recommendations. In any environment with properly trained staff (not to mention say a UL inspection) it will never be accepted.
https://cdn.thomasnet.com/ccp/00142951/263810.pdf
https://www.eptac.com/ask/when-to-tin-and-not-tin-wires/