Meh, the only working free/paid accelerator online that I know is viaBTC, others are fakes or rebroadcaster marketed as accelerator.

Your examples:
∙ bitaccelerate isn't an accelerator, they unintentionally self-confessed that they are using the term "accelerate" incorrectly through this message on their page:
∙ confirmtx is probably a scam and their thread has been receiving a lot of warnings and bad experiences from users.