You do not need to install H_C. There is a standalone portable version of FirewallHardening available:
Utility for configuring Windows 10 built-in Defender antivirus settings. - ConfigureDefender/H_C_HardeningTools.zip at master · AndyFul/ConfigureDefender
github.com
You can download it and keep it together with SWH. Next, the "C:\Windows|Hard_Configurator" folder can be deleted to remove the H_C files. The SWH and H_C are not fully compatible, so run SWH again to see if everything is OK.
I would recommend you to stop the hardening for a while and use the current setup (SWH + FirewallHardening). This reduces the attack surface significantly without losing usability. If there will not be the issues, then after a month or two you can go further (this will require some learning).
Please remember, that custom hardening will require looking at the SWH and FirewallHardening Logs (from time to time) to see for the possible block events.
You can use in SWH the option <Elevation of unsigned executables> = Restricted, if you mostly use digitally signed applications. If not then some unsigned applications will be blocked by this setting.