I think the scale from 0 to 5 is not accurate enough for the quality of the translations in the memory.
It would also benefit me for displaying it in the UI. I'm planning to use the html element called "meter" to display the quality, where the values can range from min to max value. I believe values from 0-10 would be more accurate and for the user it would be easier to decide which suggestion is better.
I would propose to change the quality scale to 10.