Were any Russian troops present during the battles of Hoogstraten and Merxem/Merksem in January and February 1814? 11 Jan 1814 Battle of Hoogstraten (Bülow) 13 Jan 1814 First Battle of Merxem (Bülow & Graham)
2 Feb 1814 Second Battle of Merxem (Bülow & Graham)
Alexander Benckendorff's (former) corps including Stahl II's and Knipper's brigades was close, as was Chernyshev's flying column, but I haven't been able to pinpoint those. If any Russians were present, the most likely ones would be cossacks under Bülow.
I can't speak with certainty for Hoogstraten, although I do not believe there to have been any Russian troops there, but there were certainly none in the two Merxem actions, which I researched for my book on Graham's campaign. The only Russians that the British troops encountered were Benckendorff's troops at Breda earlier in the campaign.