I have played TGC for years, and after adapting to the swing actions, was able to play very consistently.
I have been playing TGC 2019 for a couple of months, without much luck with the new swing (tempo-based,) until I discovered a method that corrects one aspect of my swing (I use a mouse) that made the game playable again.
The technique I devised consists of using the right or left edge of the screen as a guide. This is only possible because the lateral movement of the mouse is arrested once the mouse pointer contacts the edge of the screen. As long as I keep the mouse against the edge of the screen ( I use the left edge) during both upswing and downswing, the swing (as shown on the swing diagram) is always strait as an arrow. This method eliminates only one variable, but it allows me to swing more quickly in each direction, since I don't have to worry about lateral movement during the swing. I can achieve perfect/perfect/100% most of the time now, when before that was a rarity for me.
This will not fix bad tempo or improper wind/slope correction, but it makes it easier to concentrate on those factors.
I hope this helps others, since I have read of many players giving up pretty quickly on this game after playing the original TGC game.
Some other hints:
1) Hitting from heavy rough = add 2 clubs
2) Hitting from light rough = add 1 club
3) Hitting from greenside bunker = add 1 club with higher loft to clear the edge.
4) Hitting from fairway bunker = add 2 clubs
5) Longer drives = fast backswing, wait until player starts backswing, then fast downswing.
6) Putting distance is unaffected by swing speed, but longer delay is required. I wait until player has nearly completed the backswing before moving the mouse forward.
7) Use bottom edge to prevent too long of a backswing.