There will not be any conflict, you should use full tree of classes to affect content style, here are the wrapper classes:

#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-content .wpforo-profile-home{ }
#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-content .wpforo-profile-account{ }
#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-content .wpforo-activity-content{ }
#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-content .wpforo-sbn-content{ }

I have tried the following in the custom CSS box as well as the colors.css with no avail. 

#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-content .wpforo-profile-home{color:#F4F4F4 !important; }
#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-content .wpforo-profile-account{color:#F4F4F4 !important; }
#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-content .wpforo-activity-content{color:#F4F4F4 !important; }
#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-content .wpforo-sbn-content{color:#F4F4F4 !important; }

I have found a work around for this if anyone is interested. I have a Custom CSS plugin that overrides CSS.

#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-field input[type="text"] {
    color: #ffffff;
}
#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-field select {
    color: #FFFFFF;
}
#wpforo #wpforo-wrap .wpforo-profile-wrap .wpforo-profile-field textarea{
    color: #FFFFFF;
}
#wpforo #wpforo-wrap .wpf-topic-create .wpf-subject {
     color:#FFFFFF;
}

This will change all input fields in the profile page to be #FFFFFF, I did this because I wanted a dark nav bar but my profile text fields also have a dark background. This also makes the "Forum Post Subject Title" the same colour. 

 Attachment after the edits.