The phrase "are otherwise difficult to" is correct and usable in written English.
It can be used when discussing something that is challenging or complicated in different circumstances or contexts.
Example: "These tasks are otherwise difficult to complete without proper guidance."
Alternatives: "are hard to" or "are challenging to".
Light-responsive organic inorganic interfaces offer experimental opportunities that are otherwise difficult to achieve.
By tracking the signals, the researchers can find the nests, which are otherwise difficult to locate.
Orangutans fashion tools to extract seeds that are otherwise difficult to obtain.
Tunnel drilling provides a unique opportunity to sample and study deep groundwaters that are otherwise difficult to access.
This methodology represents a novel condition monitoring approach for the detection of chemical changes that are otherwise difficult to analyze.
The model provides data on lumbar segmental and intersegmental motion patterns that are otherwise difficult to obtain experimentally.
Consequently the iterative MOOD loop allows the numerical solution to maintain some interesting properties such as positivity, mesh validity, etc., which are otherwise difficult to ensure.
We expect this general approach will be applicable to other bulk metallic glass composites, and especially beneficial for marginal glass formers that are otherwise difficult to process.
Such information provide important information about optimal operating conditions corresponding to different trade-offs among objectives, which are otherwise difficult to obtain.
Induced pluripotent stem cells (iPSCs) are an essential tool for studying cellular differentiation and cell types that are otherwise difficult to access.
This can help "leverage the kinds of long-term institutional changes that are otherwise difficult to bring about in local education systems," according to the report.
