using below sed command, we can update the specific tag value:-

sed -i '/com.sun.faces.numberOfViewsInSession</param-name>/{n;s/3</param-value>/25</param-value>/}' test.xml

using below sed command, we can update the specific tag value:-

sed -i '/<param-name>com.sun.faces.numberOfViewsInSession<\/param-name>/{n;s/<param-value>3<\/param-value>/<param-value>25<\/param-value>/}' test.xml