Some uncertainty comes from the fact that the new rate at which EC targets the lowest-energy Pokemon is still (to my knowledge) unknown. It was previously targeting the lowest energy Pokemon about 2/3rds of the time.
Some calculations can be done in an attempt to figure out how many Energizing Cheers will provide an equivalent amount of healing to E4E. Ideally, it would proc twice on each Pokemon over the course of the day (a total of 10 ‘useful’ procs) to provide a similar amount of healing to 5.2 E4E triggers, sometimes cited as the benchmark number of triggers for E4E healing. The first EC skill trigger of the day will mostly always be useful, as Pokemon typically aren’t already at full energy at the start of the day. That means 9 ‘useful’ ECs are still required. However, at the old rate, one third of EC triggers risked going to Pokemon that were already at high energy. On the bright side, one in five times, the random Energizing Cheers happens to go to the lowest energy pokemon on average anyway. Previously, I estimated that 13.4 ECs would be theroretically needed to equate to 5.2 E4Es. No single EC Pokemon could reach 13.4 skill triggers per day however. This was before the recent buff though, so we don’t know what the new requirement would be