I’ve got, but haven’t played 1914. However, we’ve played the similar systems Iron Cross and Seven Days to the Rhine. I rather liked the latter system. Perhaps not terribly “realistic” but it was a fun club game.
I have them but haven’t played them yet due to my gaming chum not being around due to working from home at present. Some parts I can’t quite get my head around, but I too couldn’t find any online support. Normally I would expect the GEG forum to have a sub-section for them but last time I checked they didn’t. Maybe the rules just didn’t sell well enough to warrant one?