Okay; noting that the argument has moved from "untested" to "relatively untested".
To clarify, is your concern the inadequacy of the approval process FDA uses for (all) vaccines (noting that many vaccines --e.g. influenza-- are refreshed on a fairly regular basis to account for new strains of viruses) or something specific to approval of the MRNA vaccines?
Or is it that MRNA vaccines were a new approach for vaccines more generally, and so there wasn't/isn't the same long-term data that there was/is for multiple generations of vaccines based on older technologies (viral vector, toxoid, etc.)?
I disagree; "untested" is a very definitive statement. Not tested. Especially when it's in a thread discussing people using all manner of less tested or sometimes literally untested peptides. (Hence my initial thought that maybe you were aware of people taking a DIY route that I wasn't.)
Anyway, when discussing a subject so popularly controversial as vaccines, it's probably better to be precise.