A sponsor can make an offer to provide economic support and member states are allowed to have instruments that they can use to make the offer binding. You seem to have already examined the instrument the Netherlands uses and have concluded that it does not suit your needs. You want to know if your sponsor can submit an attestation of good character on your behalf.
wondering if we can make something like this work in order to
strengthen our case?
No full stop. A sponsor cannot guarantee that an applicant will honour the terms and conditions of their visa. The rationale is quite simple: people are not telepathic and so a sponsor has no way of knowing your intent. Moreover, it is empirically sound to state that close friends and relatives will not turn an abuser over to the authorities (that activity falls to neighbours and co-workers and spurned lovers who are not generally sponsors anyway).
Instead, close friends and relatives may be prone to harbouring and this is something to consider very carefully in how your material is presented.
There is nothing in the Visa Code that says a person is forbidden from submitting an attestation of good character on behalf of an applicant, but this type of evidence is ignored and in the worst case demonstrates naivety in understanding how visa decisions are actually made. There are some horrible examples floating around on the net; avoid them.
This might sound unnecessary to most of you but we're from a country
that isn't very well received in Europe or North America, so....
There are some nationalities where their performance history is unfortunate. This can make things more awkward for innocent and well-intended applicants. One 'work-around' that I have used successfully is to elaborate/expose an elevated social standing for the applicant and his family. Maybe such a strategy will work for you.
