Our best bet is that these characters make up the Tracksuit Mafia (sometimes referred to as the Tracksuit Draculas) from the comics, which was also reported by MCU Cosmic back in February. This group has intricate connections with both Hawkeye and Kate Bishop in the pages of Marvel Comics, so it will be interesting to see if they are the ones brought to the small screen when Hawkeye makes its debut.
News:According to an insider who has been a very reliable source for industry info relating to the MCU, the Hawkeye mini-series is currently casting for Eastern European actors to play a gang of mobsters who will appear in multiple episodes. Audition notes describe a scene where these mobsters break into a guarded building to retrieve an object that had been stolen from them. The context of the scene and the dialogue throughout it indicate that this object is some type of Novichok agent (chemical weapon).
This news lines up well with another exclusive from The Illuminerdi that revealed the series was casting for a 20-30 year old Eastern European actor for a character with the codename “Arek,” set to be in multiple episodes just like this gang. Whether that character turns out to be Ivan Banionis, Kazimierz Kazimierczak or somebody different, it seems likely that this character will be the leader of the mobster gang causing this mayhem.