Board Thread:Support Requests - Getting Technical/@comment-9605025-20170102050208

According to Help:Infoboxes/Tags, the image tag has the alt tag as a child. In turn, Help:Infoboxes/Tags shows how the alt tag contents are supposed to be used. Looking online about how the CSS img tag is used, I am lead to believe that this:

Some Template: Hi There Default Text

Some Page:

should result in showing "Default Text". However, as can be seen below, this is not the case.

Could someone please explain under what context the content of the alt tag will be displayed? Also, it appears that other tags such as have no effect when inside the format tag. Is there a way to specially format the content of a single cell in the infobox? 