I had been messing around in the Food&Snacks scenario, but I didn't save a place where it was convenient to recreate the bug.
Given that the Scenarios have the DLCs de-activated, I thought it would be a better test to try to reproduce it in the main game with all DLCs active.
I started a new game and created a situation where I could reproduce the bug, and succeeded!
All 3 Bugs have been reproduced.
I have included a save-file which can demonstrate 3 Bugs:
Bug #1: Relocating a firm to land you
own fails when you have enough cash to rebuild the firm
but not all of its production units.
Bug #2: Relocating a firm to land you
don't own succeeds when it shouldn't, and
costs less than the stated price.
(The stated price is wrong, as per bug #1)
Bug #3: Duplicating a firm, when you have enough cash to Build the Firm, but not it's production units, will succeed, and send you into negative cash.[/b]
(Land ownership does not seem to matter here.)

- caplab relocation bug reproduced 2.png (1.86 MiB) Viewed 2374 times
Steps to Reproduce:
(1) Attempt to Relocate the "Large Soup Factory" to the 4x4 site adjacent to it.
-It will open the factory menu, but the firm
will not have moved.
(2) Sell that 4x4 plot of land and attempt to relocate.
-It will succeed, but you will have $486,329 in cash remaining, instead of the $226,242 that the numbers say you should.
Note that both of these numbers are wrong, since they disregard the cost of the Production Units
(3) Load the save-file again.
(4) Attempt to Duplicate the factory into the 4x4 zone of land adjacent to the original. This will succeed, but send your cash to
$-794,197.
(5) Sell the land first, and then Duplicate the Factory into that location. This will succeed, and once again send your cash into the negatives.
Overall, there seems to be an error with two different ways of calculating the cost of a Relocation/Duplication.
-The "Nominal Cost" is just the cost of Land + Building
-The "True Cost" is the cost of Land + Building + Units
Different situations will either use one cost or the other. Ideally only the "True Cost" should be used for all situations.