Is it safe to change automatic meta descriptions

[ptityop]

So, we have over 1000 products for al of which the meta description is generated by prestashop. The pb is that the meta descriptions do not contain main keywords which if i undertsand is better for better ranking. My question is , is it safe to not change autogenerated meta descriprions for products but copy and paste the generated one and add products keyword in them ?

For example in the screenshots you will see a product named "Foreuse diamant ...", the auto generated description shows in google, what if I copy the same description but only adding the main keyword that does not show in google description ? Can this have negative effect or only positive ?

In the search resuts as you will see the description comes out but I understand that it is better to have the keywords in description as well. Another option would be to modify the product descriptions only and add the keywords there ... What would you suggest ? Thanks