There was little use for cavalry during the battle. The battlefield is mostly woods with scattered fields. At the end of the first day's fighting Forrest moved forward and gained a good vantage point on some old Indian mounds to watch the landing. He saw Buell's army coming across the river to swell Grant's ranks. He knew that Beauregard needed this information right away so that he could either order a night attack or prepare for a morning retreat. He was unable to find Beauregard but did find Hardee. Hardee refused to do anything about the information.
Hardee and Forrest should have known where to find Beauregard. They both should have been in contact with Johnston/Beauregard throughout the day. There is no alternate decision here because there is no way to find Beauregard to let him make a decision. Also Hardee decides not to make the decision for Beauregard.
The fact that Forrest made a reconnaissance is not a battle altering decision, that is exactly what cavalry should be doing. His efforts to share this information are dealt with in the Confederate preparations for a second day of fighting. Hardee's decision to do nothing about the information is critical because he could have made a decision to get at least part of the army ready for a second day of battle. Hardee should have realized that Beauregard was not doing anything to prepare for a second day and that he was the only one with the important information about Buell. Forrest's decision to stop looking for Beauregard is also critical because his information is so important. Forrest never did contact Beauregard because once the attack starts the value of the information was severely diminished. On the other hand the Union advance starts so early on April 7 that there is probably very little Beauregard could have done differently if he had received the information around the time of the Union advance.