The phrase "render difficult" is correct and usable in written English.
You can use it when you want to describe something that makes a task, process, or situation more difficult or challenging. For example, "The lack of proper funding has rendered the project difficult to complete on time."
These sets often have very complicated shapes (nonconvex, and even non-connected), which render difficult their manipulation.
Such oils are characterized by a low API gravity (< 20) and high viscosity (> 103 cP at 298.15 K) that render difficult oil flow through pipelines.
Tracking data may be sparse and not particularly accurate, the objects' complicate shape and unknown attitude evolution may render difficult the aerodynamic computations and, last but not the least, the models used to predict the air density at the altitudes of interest, as a function of solar and geomagnetic activity, are affected by significant uncertainties.
On the other hand, the landing of marines in Constantinople seems to have an ulterior object other than the mere protection of foreigners, so that American participation might create a dangerous precedent which would render difficult the maintenance of the Monroe Doctrine when similar troubles arise on the American continent.
The errors affecting the Q n fractions determined by Raman or 29Si NMR spectroscopy combined with those affecting the determination of the concentrations of total OH groups render difficult the detection of such a low amount.
In addition, hotspots of species richness, for different taxa rarely coincide with the lowest correlation at finer spatial scales, which render difficult the definition of an indicator taxon or even combinations of several indicators supposedly representative of the diversity in other forms of organisms [14].
However, exact bioactivity quantification was rendered difficult by the protein concentration decrease during storage.
However, the complex chemical composition of GO renders difficult to unravel the correlation between structural and electric properties.
It is also brought into action when vision is rendered difficult either by distance or the absence of sufficient light.
Calculation of the most singular point of the system herein is rendered difficult by both its size and possession of non-differentiable variables.
In practice, the accurate extraction of the impulse response is rendered difficult by the mathematical and computational properties of the power cepstrum procedure.
