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Like much of modern art, its heavy on shapes ambiguously interacting with and relating to one another.  At a glance it's easy enough to understand the literal composition of the images (e.g., there's an open door, there's some water, and there's at least two people in it, and at least one of them's reading).  But with more than a glance, the image becomes frustrating and invites one to doubt whatever meaning one may have extracted at a glance (besides the fact that it's ugly).
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There's nothing wrong, as such, with artistic symbolism (even in religious art) having multiple meanings. A hare, for instance, can represent defenseless man who puts his faith and hope in Christ Jesus.  It can also represent or allude to lust (we're all probably familiar with the axiom of "breeding like rabbits"); and for this second reason may be placed near the feet of the Blessed Mother as an indicator of her "triumph over" lust (or spotlessness and complete removal from lust, if one prefers to put it that way, given that she was sinless in the first place).  But ambiguity is different from an actual multiplicity of meaning, because where there is a multiplicity of meaning context tends to emphasize that which is intended.
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Take now the three stars on the two coats of arms.  These might refer to the Great lakes, but they also no doubt are Trinitarian in a sense, and in the first coat of arms they are placed on the beam of the cross, showing an inseparable connection between the cross and the Holy Trinity.  Makes sense, right?  After all, Christ the God-man is an inseparable person of the Triune-Godhead.  The last prayer in the offertory is an offering of Christ to the Holy Trinity.
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Now here we have the Trinitarian symbols removed from the cross, and the cross itself is simple ornamentation on the open door, over which the stars hover.  So, if nothing else, the diocese no longer associate's the symbol of the cross with the symbol of the Trinity.  The three stars aren't really related to anything in the new coat of arms.  They're just there.  
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One might also find objection in the two-person image on the left panel of the coat.  Why two different types and colors of halos?  To represent the different "types" of faith, perhaps?  And let's not ignore the obvious-- these two figures look like they're wearing hijabs.  Deerborn, anyone?