We’ve had many discussions about the Sutta Central search function here and here and here and here … a final resolution is still in the works!
I created a custom Google search for SuttaCentral some time ago… you can access it at bit.ly/SuttaCentral - Using this for your search term of “mahanidana sutta” will get you the following result…
Another possible workaround is to use voice.suttacentral.net which gets you…
We certainly do need to improve the native search function on SuttaCentral though (currently we are using Elastic search)… let me assure you that the team, led by Ven @sujato is on it!!