Talk of a silent JF17 is just that, talk.
VLO is not something you can jerry rig onto an existing design, and certainly not for something as small as the JF17 since there would be no way to incorporate even semi-internal weapons bays like those on the Silent Eagle. Without internal carrage of weapons all attempts to reduce RCS to VLO levels on the airframe is just wasted effort.
Even a silent J10 makes little sense given how much work would be needed to achieve mediocre results. You might as well just start fresh and design a light, cheap(ish) 5th gen from the ground up, which, funnily enough, is what the J31 is supposed to be. The fact that the J31 is flying already really makes any talk of a silent JF17 or J10 rather pointless since you will almost certainly get a far better 5th gen with the J31 than any silent JF17 or J10. The delivery date and pricing may also not be all that different either.
The biggest problem with the J31 is its maker, who hasn't covered itself in glory with the J11A saga, and who is a serial looser to to CAC when it comes to internal PLA competitions.
That means both the PLA and potential foreign customers are skiddish about investing the kind of money needed to make the J31 operational quickly. The secrecy surrounding the J31 also makes it hard for interested foreign customers to get enough info to decide that this is a project they would like to invest in even if they are not put off by SAC's reputation.
I see great potential in the J31, if it was a CAC project that is progressing at a similar clip to the J20, I can easily see it becoming the Mig21 of the 5th gen market and become a real competitor to the F35.
But unless SAC can get a big powerful backer with deep pockets to commit fully to the J31, and commit soon, I fear that even if it does become operational, it may do so too late in the day and end up as the JF17 of 5th gen fighters in that it, like the JF17, might be a perfectly respectable contender to other types in its class, but it would enter the market far too late to have much chance of achieving much market share.