The phrase "are yet lacking in" is correct and usable in written English.
It can be used to indicate that something is still missing or insufficient at the present time.
Example: "Despite their efforts, the team are yet lacking in the necessary resources to complete the project."
Alternatives: "are still missing" or "have yet to acquire".
However evidence of a relationship between RQUICKI and metabolic diseases in dairy cows is yet lacking.
Developing a paradigm to experimentally investigate the formation and the manipulation of spontaneous positive images would therefore aid investigation of this phenomenon and enable us to explore how an experience that may be beneficial, yet lacking, in depression may even become unhelpful in mania.
Countries like Saudi Arabia and Bahrain, which have spawned relatively many terrorists, are economically well off yet lacking in civil liberties.
That account would be good for morale yet lacking in candour.
They say that cultural diversity in research settings is crucial but point out that some international students are "too obedient" or "hard working yet lacking in originality". Without training in cultural sensitivity, they are often surprised and occasionally make errors of communication.
This deep-water area is increasingly exploited for hydrocarbons, yet lacking in baseline biological information.
In particular, a discussion on collateral consequences is included in the corporate charging guidance, yet lacking in the individual charging guidance.
The general account being of this nature, the account of particular cases is yet more lacking in exactness; for... the agents themselves must in each case consider what is appropriate to the occasion, as happens also in the art of medicine or of navigation".
The problem with applying heuristic search in probabilistic planning is that effective heuristics are as yet lacking.
