well with the currents involved it is an important matter and most other matters are resolved, I will take your suggetion and use copper wire soldered on to increase current capacity, the working environment could also be "warm"
One point to mention about soldering tin enforced traces:
They are against VDE and CE regulations and marketing items with that technique is prohibited in Europe (and elsewhere in the world).
The reason is: Hot (>183 or 205deg/C) soldering tin melts and floods the enclosure of the device causing hazardous or dangerous malfunctions.
I recently designed a power supply for 13.8V/40A. The traces are 39mm wide on 70µm copper PCB material.
Some 40 years ago I opened a Siemens high current power supply. All high current traces were enforced with rails resembling a cattle fence. There were "poles" every 10mm carring a 5X3mm copper bar mounted on the component side at 5mm distance from the board surface.
These "fences" would be the best solution I guess, but I haven't seen them since.
yes I had also considered that althogth it is convenient for them to be on the PCB at least for the 20 A versionat the end of the day I will still have to solder the wires on
I don't see why it's banned, a suitable fuse will prevent that from happening.
Overloading cables with thermosoftening insulation is just as dangerous, the surrounding insulation melts, then when the conductors come into contact with each other an arc can from which will set fire to the melted insulation but the nanny EU hasn't banned them/ Again the hazard can be mitigated by adding a suitable fuse to protect against overloading.
All wiring/conductors should be selected and rated to account for the maximum temperature ratings.
Thermosoftening cable insulation will fail long before the solder melts, yet it hasn't been banned.
If the fuse is selected to blow before the traces get hot enough to melt (given the high ambient temperature) then it won't happen.
If the traces could get hot enough to melt without an overload then they're underrated.
If the ambient temperature inside the enclosure is high enough to melt solder then you have a problem, even if you haven't used solder loaded traces it will probably catch fire soon anyway. If the equipment is so poorly designed that this could happen due to all common failure modes then it will fail to meet the minimum safety standards for CE marking anyway.
I think molten plastic is more dangerous than molten solder, even though the melting point is lower, plastic will stick to the skin causing deep severe burns, solder will just run off the skin.