Starting from Catalina only 64-bit will be allowed to run, otherwise you see a warning:
![image](https://user-images.githubusercontent.com/602540/85116590-21a7e300-b250-11ea-9cbd-7b65f9cc960d.png)


And compiling Treesheet from source code is a bit tricky.
Luckily I found that in the CI worfkflow the daily builds already in 64-bit.

Here is where you can find it. Goto the actions from [official repository](https://github.com/aardappel/treesheets),
and click on the latest successful build, eg: `https://github.com/aardappel/treesheets/actions/runs/119194981`

For unkown reason for me, the app opens default in Italian, here is the workaround that I use to force it back in English:
After unzip and go inside the *.app/ from command-line:
```
$ cd ~/Downloads/Mac\ TreeSheets/TreeSheets.app/Contents/Resources/translations
# remove or move all other translations folders into a temporary directory:
$ mkdir temp; mv * temp/
```
Try open the TreeSheets.app again