Short answer: No, enabling the reverse proxy option will not interfere with the CloudFlare service.
Long answer: CloudFlare has this plugin [1] to fix the IP address of sites that are behind their proxy, Sucuri has a similar code working in the WAF plugin [2] and the scanner plugin [3] to fix the same thing with the IP address for sites that are behind CloudProxy [4].
It should not interfere, it is actually recommended to enable this option if you are using CloudProxy and want to see the real IP addresses in the security logs, if you keep it disabled the plugin will always display the address of the reverse proxy.
If the option is enabled the Sucuri plugin will walk through this list of HTTP headers checking if they are available in the global server variable, when a coincidence is found the iteration is interrupted and the address assigned to the header is used as the real IP of the connection.
- HTTP_X_SUCURI_CLIENTIP
- HTTP_X_REAL_IP
- HTTP_CLIENT_IP
- HTTP_X_FORWARDED_FOR
- HTTP_X_FORWARDED
- HTTP_FORWARDED_FOR
- HTTP_FORWARDED
- SUCURI_RIP
- REMOTE_ADDR
As I understand CloudFlare uses a different custom header named “HTTP_CF_CONNECTING_IP” which you can see is not in the list, so I recommend you to install their plugin if what you want is to fix the problem with the misleading IP addresses in the logs.
[1] https://ww.wp.xz.cn/plugins/cloudflare/
[2] https://ww.wp.xz.cn/plugins/sucuri-cloudproxy-waf/
[3] https://ww.wp.xz.cn/plugins/sucuri-scanner/
[4] https://sucuri.net/website-firewall/
