When a matching rule has Address Equivalents ticked, we search for every abbreviation of every recognised word and combine them. For example, "123 North Main Street Apartment 4" has 72 spelling variations in a single Blackbaud query (3 x 3 x 8 = 72), which a large database cannot run in time. Rows with ordinary addresses sending 3 to 9 spellings variations work fine.
To stop the system overloading, equivalent are now capped at 12 variations. Above that we send a 'bounded set' instead: the address as given, the all-abbreviated form (123 N Main St # 4), the all-expanded form, and every version with a single word changed. That is about 14 spellings for the address above. What we no longer try are mixed forms with two or more words abbreviated differently, which are the least common way a record is keyed. Below the cap nothing has changed.
What this means in practice: nothing needs changing in your templates. However, you might notice that Importacular reports an address rule not matching a record that is keyed in an unusual mixed form