clarification for inline with non-source content

In section "5.9.7.3.2 Inline Elements" a warning says:

"Preserving source elements content that is in other than the main source
language as original data stored outside of the
translatable content at the unit level and referenced from placeholder codes is
NOT advised, as important context would be very
likely hidden from translators, human or machine."

If it really says this: "Using inline codes to preserving source content that is
not in the source language is not advised".

Then the sentence could (should) probably be reworded to be simpler and clearer.