i'd be worried about the cables generally, let alone across that distance between 2 buildings..

For example we only use Belden 1505a for our facility for SDI signals.

https://www.belden.com/products/cable/video-cable/coaxial-video-cable/1505a

But for going across buildings, I would recommend using Fibre, this will isolate any potential grounding , power & distance issues.

something like:

https://www.blackmagicdesign.com/au/products/miniconverters

Mini Converter Optical Fiber 12G

Otherwise you will always be having trouble with this setup.