Any software that I've ever tried for working with ODF's xml has been very unpleasant--either too slow or somehow unable to cope with OOo's "all in one line" xml, or an xml file that OOo has made a hash of.
I generally use two command-line utilities and a plain text editor. Emacs is my text editor; xmlindent is handy to re-format OOo's all-in-one-line xml, and xmllint tries to check an xml file for errors.
In this case, the problem turned out to be very easy to deal with.
Xmllint gave me this output:
$ xmlindent -i2 content.xml | xmllint -noout -
-:4725: parser error : Attribute table:end-cell-address redefined
-:4725: parser error : Attribute table:end-x redefined
-:4725: parser error : Attribute table:end-y redefined
-:4725: parser error : Attribute draw:z-index redefined
Line 4725 looks like this:
<table:table-cell table:end-cell-address="'Kasboek per dag'.J42" table:end-x="0.926cm" table:end-y="0.417cm" draw:z-index="0" table:end-cell-address="'Kasboek per dag'.J40" table:end-x="0.476cm" table:end-y="0.365cm" draw:z-index="0" table:style-name="ce251" office:value-type="string" table:number-columns-spanned="6" table:number-rows-spanned="2">
You can see that four of the attributes appear twice in the same xml element. That's not allowed, so the xml is not valid and won't be loaded.
I used a text editor to remove the first set of attribute values, leaving only the second set, shown in blue. I then updated the content.xml file in your document with the modified one and that opened without errors in Calc.