Lightroom 4 crashing

A guide to downgrading OS X.

https://www.macworld.co.uk/how-to/mac-software/how-remove-macos-high-sierra-downgrade-3581872/

Also, with regards to the option of purchasing LR 6.14, please be aware that there will be no further update to your software, no bug fixes; and if a future version of your operating system breaks 6.14, there will be no fix. None of this is true for Lightroom Classic CC (part of the Photography Plan)

LR 4 does not run properly, if at all, on Mac OS X High Sierra.

If you want to continue using LR you will need to either downgrade your version of OS X, if that is even possible, or upgrade LR to either LR 6.14, one time cost, or subscribe to the Photography plan subscription, a monthly fee of $9.99 US, that also includes Photoshop.

Since you are using a slightly older Mac you can probably downgrade OS X to a previous version but to do so you would need to erase the hard drive and then reinstall everything. OS and Programs and have a current backup of all your personal files including all your images files.

Apple does not allow you to easily go back to a previous version of OS X like Microsoft does with Windows.