Search pages using Acquia Search and Search API have problems including improper or buggy highlighting, autocomplete, matching, etc.
A possible solution is to disable various Processors in the Search API Index settings and reindex.
The list of processors to disable when using a Solr / Acquia Search backend are:
NOTE: You will now need to handle any custom manipulation (for example, any special stopwords ) using Custom Solr Configuration.
Search API Processors are meant to pre-process the data at indexing time using PHP, before sending it to the backend.
When using a Solr or Acquia Search backend, you should avoid the use of various of these processors, as they are actually already part of the standard Solr configuration and similar data processing already happens there.
On the other hand, using these processors is acceptable when using a Database backend it does not natively handle these data processing activities.