This is one of the albums I listen to mainly for the abundant quality sebenes showcasing Caen Madoka, Oceane, and Lofombo
I noticed many big-soukous stars of that time where not really great singers.
Indeed, they weren't exactly known for their compositions either. That's why in the soukous era they all did a sebene introduction, 1-2mins of slow singing, then the rest sebene by skilled guitarists and usually 3615 on shakers/animation to offset things. Once dance music declined, they were the first to disappear.
Aurlus was a decent singer in his very early days, but he never had a natural singing voice, which became noticeable as he aged. Diblo sang on his solo albums, and for how amazing of guitarist he is, his singing is just catastrophically bad