We put this question to Shaykh ‘Abd al-Rahmaan ibn Jibreen (may Allaah preserve him) and he answered:
If that does not take space away from the worshippers, and it is not spending money that was endowed to the mosque in a waqf, and that the mosque needs it or there are people who need it, then there is nothing wrong with that being an adornment to the mosque.
And Allaah knows best.