I guess this is an x-y-question.
I am afraid your confusing references are caused by the non-systematic numbering in your examples. In case you have lots of references and lots of item classes to refer to, you should invest a bit more sophistication in your numbering and invent a numbering system that embraces the item class.
Even if you were finding good abbreviations for all the item classes (which I doubt for the full list), it would make your document not much more readable.
If you do your numbering right (unique between classes), you can simply refer to the numbers instead of using cryptic abbreviations. In the example above, number the lemmas as L 5.2.19, the text boxes as T1.2.8, the characteristics as C6.3.7. Then it is very clear to the reader from the number already what item class you are referring to. Good math text books do it that way.
Your cryptic reference will then boil down to
In L5.2.11 - L5.2.19 bereiten wir unter Berücksichtigung von TK1.2.8-TK1.2.11 die Grundlagen für C6.3.7 vor.
Also makes it much clearer to what you are referring to, and makes the creation of indices and lists of "items" much easier to handle. Also, the references themselves will be much easier to write.
Obviously, you need to introduce your reader to your numbering system in an early paragraph.