The phrase "relatively reliable" is correct and can be used in written English.
You can use it when referring to something which is not completely reliable, but can still be relied upon to some degree. For example, "The bus schedule is relatively reliable, so you can usually arrive at your destination on time."
The machine was relatively reliable (it normally ran all night unattended), but it had no decision-making ability.
In fact, it's not a figure chosen entirely because of neatness but seems to be a relatively reliable benchmark for competence.
They have used it to avoid taxes and political risk at home and to access Cyprus's relatively reliable court system to adjudicate disputes.
So we ended up with a relatively reliable but inflexible system that has proved unable to take advantage of changing technology.
On Friday, Southern announced it would be restoring 16 of those services after a relatively reliable week, with 80% of scheduled trains arriving on time, compared with about 60% when the normal timetable was running.
Starting in the nineteen-seventies, cheap air travel to continental Europe, with its relatively reliable sunshine, became available to the kind of working-class holidaymakers who formerly patronized the seaside resorts first popularized in the Georgian and Victorian eras.
We've had various Saabs for more than 10 years now – all of which have been relatively reliable if expensive to maintain – as we fell time and again for their advertising spiel.
_ For much of "P.E.," we think of our narrator, Freddy, as a relatively reliable presence, whereas his father is a man who brings with him chaos and dirty laundry.
Although PV systems are relatively reliable, they may fail occasionally.
The destructive methods for SSD are relatively reliable.
After the above procedure, we can find which block is relatively reliable for target tracking.
