Localization

File .pot is probably outdated. Line numbers do not correspond to the file .php and there is no line “Exclude from Search?”.

Also not prepared for translation the block

<?php
	global $wpdb, $wp_version;
	echo "<h3>Support</h3>\n";
	echo "<p>Please report this information to <i>mclark -at- planetmike.com</i> if you have trouble with this plugin. Thanks!</p>";
	echo '<ul>';
	echo '<li>UCE version: 0.96</li>';
	echo '<li>PHP version: '.PHP_VERSION.'</li>';
	echo '<li>MySQL version: '.mysql_get_server_info($wpdb->dbh).'</li>';
	echo '<li>WordPress version: '.$wp_version.'</li>';
	$mbctheme = wp_get_theme();
	echo "<li>Theme: ".$mbctheme->Name . " is version " . $mbctheme->Version."</li>";
	$category_count = $wpdb->get_var("SELECT COUNT(*) FROM $wpdb->term_taxonomy WHERE taxonomy = 'category'");
	echo '<li>Number of categories is: '.$category_count.'</li>';
	if(!defined('AUTH_KEY')){ echo "<li>AUTH_KEY is empty. Please check your settings in your wp-config.php file. This doesn't affect UCE, but it will help make your WordPress sytem more secure.</li>"; }
	echo "</ul>";

I for myself have moved the first two lines out of the function, the result was as follows:

<h3><?php _e('Support', 'UCE') ?></h3>
	<p><?php _e('Please report this information to <i>mclark -at- planetmike.com</i> if you have trouble with this plugin. Thanks!', 'UCE') ?></p>

	<?php
	global $wpdb, $wp_version;
	echo "<ul>";
	echo '<li>UCE version: 0.96</li>';
	echo '<li>PHP version: '.PHP_VERSION.'</li>';
	echo '<li>MySQL version: '.mysql_get_server_info($wpdb->dbh).'</li>';
	echo '<li>WordPress version: '.$wp_version.'</li>';
	$mbctheme = wp_get_theme();
	echo "<li>Theme: ".$mbctheme->Name . " is version " . $mbctheme->Version."</li>";
	$category_count = $wpdb->get_var("SELECT COUNT(*) FROM $wpdb->term_taxonomy WHERE taxonomy = 'category'");
	echo '<li>Number of categories is: '.$category_count.'</li>';
	if(!defined('AUTH_KEY')){ echo "<li>AUTH_KEY is empty. Please check your settings in your wp-config.php file. This doesn't affect UCE, but it will help make your WordPress sytem more secure.</li>"; }
	echo "</ul>";

Perhaps you will find it appropriate.

If you need, I can provide the corrected file .pot and ready files .po and .mo (translated into Russian).

https://wordpress.org/plugins/ultimate-category-excluder/