Maybe I am an idiot but when I make a hole I only do a Save Scene as save and immediately when I do this I back up the terrain.
for example I make a hole 1 then I want to play test it I play test it way before it is ever even close to be completed before planting trees water changing elevations etc. I plop down 3 tees , 3 pins some fairway and test it but anyway I would 1st do a save as h1a this is hole number one version A - do not use caps then I do a terrain save with the same thing h1a for a terrain save.
If I ever have a problem which I have then I open for example scene h1a and terrain save of h1a and start back at this point knowing that at this point everything works. meaning to I have now clicked on something wrong in unity and messed it up etc.
so what happens is for each hole I may have 10 saves h1a, h1b, h1c, - h1h etc. and the same exact names for terrain saves.