One of the users at my firm was trying to link an AutoCAD file into Revit 2016, to get some formatted text notes into his project. The formatting of the text changed from what shows in AutoCAD when linked into Revit. It turned out he was using the Columns feature of MText to get his notes to wrap into a second column, as the total "height" of the notes was greater than the height of the sheet. Revit ignored the columns formatting and displayed the text as one continuous column, with the width set to match the total width of both columns in AutoCAD.
The solution was to reformat the MText in AutoCAD, removing the columns formatting, setting the overall width to that of one column, and breaking the MText into two separate pieces, one for each of the former columns. Any future edits to the AutoCAD file will have to deal with the separation of the MText into two pieces, but the text does appear as desired when linked into Revit.
One more issue that we will not encounter as often as we start using Revit 2018 on new projects, given the somewhat improved ability to format text in 2018.