The phrase "continued to be observed" is correct and usable in written English.
You can use it to describe something that has been going on for some time or is still true. For example, "Traditional religious practices in the country have continued to be observed over many generations."
Interestingly, at 20 and 25 DPA, during the onset and continuation of secondary wall synthesis, 4.5 - 8.0% differentially expressed genes continued to be observed between accessions.
In experiment two, which integrated an interactive and life-like sculpture of a human into a VR simulation, greater utilitarian actions continued to be observed.
During the Islamic conquests several generations later, an accommodation was made with local Muslim rulers, and Zoroastrian services continued to be observed on the site.
The Administration of Estates Act (1925) abolished dower in the United Kingdom, but it continued to be observed in a number of common-law jurisdictions, often in a modified form.
In contrast, sustained growth continued to be observed in the MX group from day 11.
A low level response to this antigen continued to be observed throughout the 52-week post-vaccination period (Figure 2B).
23 Since we believe that distinction should continue to be observed, we reverse the judgment of the Court of Appeals.
The four monthly holy days of ancient Buddhism, called uposatha, continue to be observed in the Theravada countries of Southeast Asia.
The cease-fire in eastern Ukraine, which both sides agreed to Monday, appeared to continue to be observed only partially Wednesday.
Substantial Arctic ozone loss also continues to be observed in the late winter/early spring of some years when polar stratospheric temperatures are particularly low.
