Disappointments and surprises of Olympus and MFT

oh bro, you bought pro body and load of consumer level lenses that are no match for it.

the 12-32mm is stunningly good, small and light,

it's compact, low performance, dark kit lens for masses, not photo enthusiasts. Your E-M1 dropped rear dial out of astonishment you paired it with such rather low grade lens.

and between it and my Olympus 12-60mm SWD there isn't a big difference (well, yes, in size!).

12-60 is very good lens, however nowadays I would advise against using any 43 optics on m43 system for performance/speed, size, maintenance, etc. reasons. Yes, E-M1 was designed to drive 43 lenses, and if it happened you bought years ago legendary Pro zooms of 43 era and don't want to sell them, then yes, use on E-M1, but otherwise - no. You should go with current m43 Pro lenses. Sell it. Buy 12-40/2.8 for the money.

On the other hand, my Olympus 14-140mm mk. I is poor.

of course it's poor. What did you expect for such aperture and resolution? Again - allrounder for masses, not photo enthusiasts.

Olympus 70-300mm FT and the 75-300mm MSC II.

these are somehow humble lenses. Can be considered only taking into account what they offer for price they are sold and size they are. Resolution is grainy and poor on these, but can be worked out in PP. You want to avoid these if you are serious about wildlife and care for quality pic.

Has anyone had good experiences with the Canon 70-200mm f/4L and some smart adapter? Or maybe the 300mm f/4L IS, or the 200mm f/2.8L II? As long as any of those can AF faster than the Olympus 70-300mm I'll be happy.

this is something you should not do. If you consider canon lens size, you should go with canon body. You won't get performance with those adapters and end up with heavy, inconvenient setup not worth effort and money. Should go with 40-150/2.8 zoom.

2) Will the Panasonic 14-140mm II be a big difference over my Olympus 14-150mm? I really want a decent travel zoom. The Tamron 14-150mm also comes to mind.

take 12-40/2.8 and you will be delighted for everyday. Sell other zooms, buy 40-150/2.8, or f4-5.6 while you saving for f2.8.