If you want to treat the first / last text nodes of article-title, no
matter how deep they are nested in other elements:

<xsl:template match="article-title//text()[
generate-id() eq (
for $t in ancestor::article-title//text()
return generate-id($t)
)[last()]
]"

 <xsl:template match="article-title//text()[
 . is(ancestor::article-title//text())[last()]
 ]"