Over 30 years ago I bought along length of orange two-core 13A cable and made up a set of jack-to-jack speaker leads. Never any issues, although I have upgraded to heavy-duty metal bodies jacks (which I then realised could cause a short more easily, so I shrouded them with heat-shrink tubing). Not easy to confuse with guitar leads (as long as I don't buy orange ones).
Bass Terror has speakon-only, new cab has Neutrik combined sockets. Speakon-speakon is fine (actually really good).
Elf has jack socket, bought a Stagg speakon-jack cable at PMT and the jack is about 1.5mm short. It works but the first time I used it in anger it vibrated out of the socket, scaring the crap out of me - I relocated the amp to the floor. So new jack-speakon required, or maybe use one of my old, orange mains leads!