[p1s4]

I know this topic is very old, but is the most recent i found about this argument.

I need different colors for authors link ( topic and replys) .

I solved using the filters bbp_get_reply_author_link and bbp_get_topic_author_link in function.php of my child theme.

I changed the class $link_class in $author_link, you can found the original code in bbpress/includes/topics/template.php and bbpress/includes/reply/template.php.

This is the complete code in my function.php child’s theme:

//custom color LINK AUTHOR roles
add_filter( 'bbp_get_reply_author_link', 'addrole_reply_author_links', 10, 2);
add_filter( 'bbp_get_topic_author_link', 'addrole_topic_author_links', 10, 2);
function addrole_topic_author_links($author_link, $args) {
// Parse arguments against default values
		$r = bbp_parse_args( $args, array(
			'post_id'    => 0,
			'link_title' => '',
			'type'       => 'both',
			'size'       => 80,
			'sep'        => ' ',
			'show_role'  => false
		), 'get_topic_author_link' );

		// Used as topic_id
		if ( is_numeric( $args ) ) {
			$topic_id = bbp_get_topic_id( $args );
		} else {
			$topic_id = bbp_get_topic_id( $r['post_id'] );
		}

		// Topic ID is good
		if ( !empty( $topic_id ) ) {

			// Get some useful topic information
			$author_url = bbp_get_topic_author_url( $topic_id );
			$anonymous  = bbp_is_topic_anonymous( $topic_id );

			// Tweak link title if empty
			if ( empty( $r['link_title'] ) ) {
				$link_title = sprintf( empty( $anonymous ) ? __( 'View %s\'s profile', 'bbpress' ) : __( 'Visit %s\'s website', 'bbpress' ), bbp_get_topic_author_display_name( $topic_id ) );

			// Use what was passed if not
			} else {
				$link_title = $r['link_title'];
			}

			// Setup title and author_links array
			$link_title   = !empty( $link_title ) ? ' title="' . esc_attr( $link_title ) . '"' : '';
			$author_links = array();

			// Get avatar
			if ( 'avatar' === $r['type'] || 'both' === $r['type'] ) {
				$author_links['avatar'] = bbp_get_topic_author_avatar( $topic_id, $r['size'] );
			}

			// Get display name
			if ( 'name' === $r['type'] || 'both' === $r['type'] ) {
				$author_links['name'] = bbp_get_topic_author_display_name( $topic_id );
			}

			// Link class
			//ADD ROLE CLASS TO LINK 
			$role        = str_replace(' ', '-', strtolower(bbp_get_user_display_role( bbp_get_topic_author_id( $topic_id )) ));
			$link_class = ' class="'.$role.' bbp-author-' . esc_attr( $r['type'] ) . '"';

			// Add links if not anonymous
			if ( empty( $anonymous ) && bbp_user_has_profile( bbp_get_topic_author_id( $topic_id ) ) ) {

				$author_link = array();

				// Assemble the links
				foreach ( $author_links as $link => $link_text ) {
					//ADD ROLE CLASS TO LINK 
					$role        =  str_replace(' ', '-', strtolower(bbp_get_user_display_role( bbp_get_topic_author_id( $topic_id )) ));
					$link_class = ' class="'.$role.'  bbp-author-' . esc_attr( $link ) . '"';
					$author_link[] = sprintf( '<a href="%1$s"%2$s%3$s>%4$s</a>', esc_url( $author_url ), $link_title, $link_class, $link_text );
				}

				if ( true === $r['show_role'] ) {
					$author_link[] = bbp_get_topic_author_role( array( 'topic_id' => $topic_id ) );
				}

				$author_link = implode( $r['sep'], $author_link );

			// No links if anonymous
			} else {
				$author_link = implode( $r['sep'], $author_links );
			}

		} else {
			$author_link = '';
		}

return $author_link;
}

function addrole_reply_author_links($author_link, $args) {

		// Parse arguments against default values
		$r = bbp_parse_args( $args, array(
			'post_id'    => 0,
			'link_title' => '',
			'type'       => 'both',
			'size'       => 80,
			'sep'        => '&nbsp;',
			'show_role'  => false
		), 'get_reply_author_link' );

		// Used as reply_id
		if ( is_numeric( $args ) ) {
			$reply_id = bbp_get_reply_id( $args );
		} else {
			$reply_id = bbp_get_reply_id( $r['post_id'] );
		}

		// Reply ID is good
		if ( !empty( $reply_id ) ) {

			// Get some useful reply information
			$author_url = bbp_get_reply_author_url( $reply_id );
			$anonymous  = bbp_is_reply_anonymous( $reply_id );

			// Tweak link title if empty
			if ( empty( $r['link_title'] ) ) {
				$link_title = sprintf( empty( $anonymous ) ? __( 'View %s\'s profile', 'bbpress' ) : __( 'Visit %s\'s website', 'bbpress' ), bbp_get_reply_author_display_name( $reply_id ) );

			// Use what was passed if not
			} else {
				$link_title = $r['link_title'];
			}

			// Setup title and author_links array
			$link_title   = !empty( $link_title ) ? ' title="' . esc_attr( $link_title ) . '"' : '';
			$author_links = array();

			// Get avatar
			if ( 'avatar' === $r['type'] || 'both' === $r['type'] ) {
				$author_links['avatar'] = bbp_get_reply_author_avatar( $reply_id, $r['size'] );
			}

			// Get display name
			if ( 'name' === $r['type']   || 'both' === $r['type'] ) {
				$author_links['name'] = bbp_get_reply_author_display_name( $reply_id );
			}

			// Link class
			//ADD ROLE CLASS TO LINK  
			$role        =  str_replace(' ', '-', strtolower(bbp_get_user_display_role( bbp_get_reply_author_id( $reply_id ) )));
			$link_class = ' class="'.$role.' bbp-author-' . esc_attr( $r['type'] ) . '"';

			// Add links if not anonymous and existing user
			if ( empty( $anonymous ) && bbp_user_has_profile( bbp_get_reply_author_id( $reply_id ) ) ) {

				$author_link = array();

				// Assemble the links
				foreach ( $author_links as $link => $link_text ) {
					//ADD ROLE CLASS TO LINK 
					$role        =  str_replace(' ', '-', strtolower(bbp_get_user_display_role( bbp_get_reply_author_id( $reply_id ) )));
					$link_class = ' class="'.$role.'  bbp-author-' . $link . '"';
					$author_link[] = sprintf( '<a href="%1$s"%2$s%3$s>%4$s</a>', esc_url( $author_url ), $link_title, $link_class, $link_text );
				}

				if ( true === $r['show_role'] ) {
					$author_link[] = bbp_get_reply_author_role( array( 'reply_id' => $reply_id ) );
				}

				$author_link = implode( $r['sep'], $author_link );

			// No links if anonymous
			} else {
				$author_link = implode( $r['sep'], $author_links );
			}

		// No replies so link is empty
		} else {
			$author_link = '';
		}

		return $author_link;
	}

Then you have to add the CSS to the new class added to author’s link.

Hope will be useful,
bye,
Marco.