In theory you can always have taller mountains if you just have a (exponentially!) wider base. But given all sorts of practical constraints, Earth mountains are pretty much limited to <10 km.
Mostly true on Earth, but not on other planets with lower gravity, and AFAIK it depends on the rock type. Hence why you have Olympus Mons on Mars (or insanely tall ice mountains on Pluto, when that material couldn't form such a steep talus angle on Earth).
Which would also serve as reasonable challenges for genetic and molecularbiological engineering so ... what's your point?
Or do you mean to suggest that the failure of any accepted tree height records to surpass the maximum capillary distance can be explained by some other factor? (Based on your other comment it seems safe to assume that isn't what you meant but anyhow.) That seems far too convenient given that the observed cutoff is within the expected range.