Had a bit of bother with that, because customtextout.txt seems to end with an unwanted CR LF that is added to the last item in the explode() array in w34_livedata.php. . .
Quick and dirty fix was to add a dummy unused tag to the end of customtext.txt, but niko pointed me in another direction: trim() the string definition in w34_livedata.php
$weather["barometer_trend"] = convert_baro ($wd[50],$from,$to);
$weather["lowbarotime"] = $customtext[9]; # tag %lowbarot%
$weather["highbarotime"] = rtrim($customtext[10]); # tag %highbarot%
Thanks, pal!