The single language cover variant is NOT a specific ‘Asian’ version.
They were distributed by SNK/UK to UK retailers alongside the tri-manual versions, and in fact, sometimes they seem to have been the only versions available. They are official UK versions. They are not ‘grey’ imports or anything else. Retailers added ELSPA labels where applicable. Some have SNK’s Osaka address, some do not. There is even a sort of ‘evolution’ within this type of packaging, as the later games actually have ‘CE’ and ‘ELSPA’ logos printed onto the inserts. ‘Asian’ or ‘Hong Kong’ versions would not need European union compliant packaging.
SNK were clearly trying various types of inserts/manual combinations. Sometimes games with tri-language inserts, were distributed with only the English manual in the UK. Other times they included all three. As was wisely stated above, It was a weird time for SNK!
I bought most of my NGPC games from officially sanctioned, and officially supplied UK high-street retailers, and I have the usual combination of insert variants.
My advise to anyone looking to collect these games would be don’t worry about it. They are all legitimate. Look at Faselei and Last Blade! Two of the later releases, all of the official UK versions that I have seen, have single manuals and single language English inserts, with ELSPA/CE logos printed on them.
My personal opinion on this matter is that SNK were less than worried about producing multi-language versions of these games. I think that they would have rather just have made the Jp and Eng lan versions. I think that as their enthusiasm waned, they tried to cut costs by printing less manuals, making less variants etc.
Although it is also strange that some versions (As the tri version in the picture above) dont have age ratings on them, but seem to have a space where one could be put?
Whereas the single lan Euro version has the Age rating. It could simply be a later print, once the censors had rated the game, that was printed specifically for the UK.