Leuconostocoeni is the correct name if this species is regarded as a separate species within a separate genus Leuconostoc.
The original spelling, Leuconostoc oenos (sic) has been corrected by Dicks et al. 1995.Publication:
Dicks LM, Dellaglio F, Collins MD. Proposal to reclassify Leuconostoc oenos as Oenococcus oeni [corrig.] gen. nov., comb. nov.. Int J Syst Bacteriol 1995; 45:395-397.