I think you would need to refer to a published source in order to make a change request to a page on Numista. I’m not sure if the Nummus Bible Database would qualify as a source. However, after reviewing the relevant OCRE pages, I think RIC can be that source. It’s just that RIC (and OCRE) aren’t very clear.
For starters, there are two separate types in RIC which cover your coin: IX Thessalonica 18B and IX Thessalonica 27B. Both types have the exact same descriptions and same subtypes, and the only discernible difference between them is that 18B covers the years 364-367, while 27B covers 367-375. This is confusing because I’m not sure how one can identify which of those periods a particular Valens coin comes from. (For reference, 367 is when Gratian was elevated to emperor, and 375 is when Valentinian I died. Valens didn’t die until 378, so following this logic there should theoretically be a third type 32C covering 375-378, but that doesn’t exist in RIC.)
The OCRE pages are also inconsistent when it comes to listing field marks and mint marks. The left field should be listed first, then the right field, then the exergue, but the listings given are often confusing. I now believe your coin would be covered under subtype xxx. The mint mark is described as M/[* on A]//TES or B or Δ, but this really should be [* on M]/A//TES or TESB or TESΔ
Numista has three pages for Valens SECVRITAS REIPVBLICAE minted in Thessalonica, but I’m of the opinion there should be just one page covering all years 364-378, with all relevant subtypes listed. At the least, Numista page 451297 should probably be deleted since it only describes a single subtype. That subtype should really be listed under the main pages for RIC types 18B and 27B.
N#97967
N#170054
N#451297