Regarding problematic documents, there are 2 cases:
1- docx created outside docx4j (eg in Word or something else eg OpenOffice). If docx4j can't open one of these, or roundtrips it incorrectly, I'd want to investigate this as a high priority. Historically, this has been rare.
2- you use docx4j to create an invalid docx (or one Word can't open). There is nothing to stop you doing this; this is generally your problem unless you can show that docx4j is doing something wrong, or you can narrow the problem down to a particular structure and ask a specific question about how to deal with it.
Often, case 2 is painful, because Word may give you no clue as to what is wrong.
In this case, Word is helpful. It says the problem is at column 41586 in document.xml. Looking there, it is immediately preceded by:-
Using xml Syntax Highlighting
<w:tr w:rsidTr="005A53AB" w:rsidR="00DA4589" w:rsidRPr="00DC4D8E">
<w:trPr>
<w:trHeight w:val="419"/>
</w:trPr>
<w:sdt>
<w:sdtPr>
<w:rPr>
<w:rStyle w:val="Arial1000Zchn"/>
</w:rPr>
<w:alias w:val="cc0050COL1"/>
<w:tag w:val="cc0050COL1"/>
<w:id w:val="7180960"/>
<w:showingPlcHdr/>
<w:text w:multiLine="true"/>
<w:dataBinding w:storeItemID="{e85a7f07-fe34-4e7b-a383-30392ff86cf5}" w:xpath="/root/cc0050COL1"/>
</w:sdtPr>
<w:sdtContent/>
</w:sdt>
<w:sdt>
<w:sdtPr>
<w:rPr>
<w:rStyle w:val="Arial1000Zchn"/>
</w:rPr>
<w:alias w:val="cc0050COL2"/>
<w:tag w:val="cc0050COL2"/>
<w:id w:val="7180964"/>
<w:showingPlcHdr/>
<w:text w:multiLine="true"/>
<w:dataBinding w:storeItemID="{e85a7f07-fe34-4e7b-a383-30392ff86cf5}" w:xpath="/root/cc0050COL2"/>
</w:sdtPr>
<w:sdtContent/>
</w:sdt>
<w:sdt>
<w:sdtPr>
<w:rPr>
<w:rStyle w:val="Arial1000Zchn"/>
</w:rPr>
<w:alias w:val="cc0050COL3"/>
<w:tag w:val="cc0050COL3"/>
<w:id w:val="7180968"/>
<w:showingPlcHdr/>
<w:text w:multiLine="true"/>
<w:dataBinding w:storeItemID="{e85a7f07-fe34-4e7b-a383-30392ff86cf5}" w:xpath="/root/cc0050COL3"/>
</w:sdtPr>
<w:sdtContent/>
</w:sdt>
</w:tr>
Parsed in 0.007 seconds, using
GeSHi 1.0.8.4
So you have a table row which contains empty <w:sdtContent/> elements, rather than <w:tc>.
Word is a bit particular about the content of w:tc, and w:tr by the looks of it.
I guess the question is whether the docx4j binding handler should be protecting you in this case or not. Possibly/probably, since we handle somewhat similar cases eg in OpenDoPE handler iirc.