"have been attempting" is correct and commonly used in written English grammar.
Example: I have been attempting to learn French for the past year, but I still struggle with basic conversation.
We have been attempting to construct artificial neural networks.
Individual peers have been attempting to protect individual public bodies.
He may have been attempting to flee to Algeria.
Scientists have been attempting to transplant eye cells for decades.
Both artists have been attempting to break through on screen.
Researchers have been attempting to engineer human stem cells so they form into functional podocytes.
We have been attempting to do the same thing with the stock market.
He noted that some reformers have been attempting to end summer vacation for decades.
Already comfortable in green, the Jets have been attempting to build that way, too.
Behind the scenes we have been attempting to negotiate with God.
Put bluntly, we have been attempting cultural change on a management consultant timeline.
