I see that mycroft-core pins that version, sothere’s no great way to update that to 0.3.1 in Picroft… You could try testing with Precise 0.2.0 (No tag for 0.2.1), but that doesn’t really help find a solution, only to further diagnose the problem.
I think at this point the best path forward would be to upgrade to a supported distribution of Neon or OVOS where you can use the latest precise WW engine, or you might have better results with Open Wake Word.