This looks like a character set mismatch. You might try changing TweetWX-forecast.php $t = preg_replace('| °|is','°',$t);
to $t = preg_replace('| °|is','',$t);
to just remove the degree sign altogether.
As for the current conditions tweets, what does the error message say?
Also, you have in Settings.php $SITE['WDdateMDY'] = true; // for WD date format of month/day/year. =false for day/month/year
but your testtags.php is showing dates like $date = '09/07/2021';
which is in D/M/Y format.
Change Settings.php to have $SITE['WDdateMDY'] = false; // for WD date format of month/day/year. =false for day/month/year
to have the dates display correctly.