Synonym for meanwhile
Solution 1:
I'm not sure 'meanwhile' is the right word to use for looking for synonyms. I think it is used idiomatically more than literally here.
'Meanwhile' means 'at the same time', but also 'concurrently', 'simultaneously', i.e. happening at the same time.
What I think your wording wants to express is something like 'on the other hand', 'however', 'nevertheless', i.e. a (seeming) contradiction. Perhaps those synonyms are helpful.