Hello,

1. As we have already mentioned in some of your previous ticket, theme labels can be changed or translated to your language with poedit software which is native wordpress way - following guide may be helpful http://code.tutsplus.com/tutorials/translating-your-theme--wp-25014 (read from point 3) or any other plugin for translation such as Loco translate plugin https://wordpress.org/plugins/loco-translate/ and here is beginners guide https://localise.biz/wordpress/plugin/beginners

2. You can try to add this css underneath in Appearance >> Customize >> Additional CSS field:

.single-course .eltdf-course-tabs-wrapper li.reviews_tab.ui-state-default.ui-corner-top {
    display:none;
}
.single-course .eltdf-course-tabs-wrapper li.members_tab.ui-state-default.ui-corner-top {
    display:none;
}
.single-course .eltdf-course-tabs-wrapper li.eltdf-custom-tab-link.ui-state-default.ui-corner-top {
        display:none;
}

Please let us know if there is anything else we can do for you.

Thank you,
Jerry, Elated