Shoshannah notes: So perhaps, after all, SHALL is the stronger of the two?

This is, of course, from an early Modern English translation and in no way reflects any Hebrew language conventions which would be irrelevant anyway. Those who use such words as shall, will and should in a context in which it is critical that they be understood as intended by the writer are well advised to make the meaning clear in the introduction or foreword to the document in which the terms are being used. In technical manuals this is usually accomplished by such statements as:

In this document when the word SHALL is used in all caps and bold print it means that failure to follow the directions can cause severe damage to equipment and personnel. When the word SHOULD is used it means that minor errors could cause improper functioning of the equipment. Whether the improper functioning will cause collateral damage is dependent on external circumstances, e.g., failure of a program to operate properly in a device that is controlling the manufacture of ice cubes may result in failure to produce ice cubes; failure of a program to operate properly in a device that is cooling a nuclear reactor may cause meltdown of the reactor and significant damage to neighboring communities.