The phrase "although substantial efforts have" is correct and usable in written English.
It can be used to introduce a contrast or exception in a statement, often leading to a conclusion or result that may seem unexpected given the efforts mentioned.
Example: "Although substantial efforts have been made to improve the system, many users still report issues."
Alternatives: "despite significant efforts having" or "even though considerable efforts have".
Although substantial efforts have been made to link β1-AR polymorphisms with cardiovascular function, studies have been mixed in this regard.
Although substantial efforts have been invested in studying the statistical power of differential gene expression [16], [17], much less is known currently about the power of testing molecular signatures for statistically significant (hence reproducible, "real") signal.
Therefore, although substantial efforts have been made to compare the viral host properties of several species [16], [18], [24], we propose there is a need for yet broader taxonomic testing among birds.
Although substantial efforts have been invested into studying this problem, the vast majority of the PCW related genes remain unknown.
Although substantial efforts have been made to delineate the mechanisms of paracetamol-induced liver destruction, the biochemical events and their cellular targets leading to the disease are still not completely understood.
Although substantial efforts have been made to curtail smoking in Vietnam, the 2010 Global Adult Tobacco Survey GATSS) revealed that the proportion of male adults currently smoking remains high at 47.4%.
Although substantial effort has been devoted during the past decades to the establishment of a testing procedure for low permeable geomaterials, no consistent protocol can be found.
Although substantial effort has been conducted into understanding mechanistic consequences of cell cell and cell environment interactions, the evolutionary and ecological outcomes have not been explicitly tested.
Although substantial effort has been devoted to understanding GH activities, structures, and mechanism of action, past efforts have been focused mostly on studying one or few enzymes at a time.
Although the etiology of RA is unknown, substantial efforts have been directed toward studying the transition of the joint from normal to diseased.
Substantial efforts have been devoted to improving the scheduling efficiency of on-demand broadcast.
