"considerably complicated" is a correct and usable phrase in written English.
It can be used to describe something that is very complex or difficult to understand. Example: The instructions for assembling the furniture were considerably complicated, and it took me several hours to put it together.
But I came out as gay in high school, which considerably complicated matters.
Both Swiss and EU officials have said the UK's vote to leave the EU had considerably complicated talks between the two sides.
That question, in turn, was considerably complicated by Supreme Court decisions in the decade since the law was passed that limited Congress's ability to breach state immunity.
The mathematics of diffraction is considerably complicated, and a detailed, systematic theory was not worked out until 1818 by the French physicist Augustin-Jean Fresnel.
The interpretation of MR in bulk matter is considerably complicated by the relationship of the spins with each other and with the other degrees of freedom of the sample.
The issue was considerably complicated by the influence of John Duns Scotus.
Their dominance considerably complicates collective-bargaining efforts for other unions.
Whitehead, a canny storyteller, makes use of this narrative tradition in "The Underground Railroad," while also considerably complicating it.
The large number of asymmetrical carbon atoms and the consequent number of possible isomers considerably complicates the structural chemistry of carbohydrates.
The most critical comment is the short half-life of 11C, which considerably complicates the widespread use of [11C]CB184.
Moreover, a MAC generally introduces correlations among node locations and, thus, considerably complicates the analysis (conf. Section 3.1).
