I think the reason why Section 4.4 of the Warrant Agreement uses the word "MAY" instead of "SHALL" is because it states both "NOT STRICTLY APPLICABLE" and "STRICTLY APPLICABLE".
For example - if Section 4.4 stated just the following in example 1. then the word "SHALL" would be most applicable. On the other hand, if Section 4.4 stated just the following in example 2. then the word "MAY" would be most applicable.
1. If an Event occurs as to which the foregoing provisions of this Article IV are NOT STRICTLY APPLICABLE, or would not ...................... fairly and adequately protect the purchase rights of the Holders .............. then the Board "SHALL" make ........................... such adjustments ............................
2. If an Event occurs as to which the foregoing provisions of this Article IV are STRICTLY APPLICABLE, but would not ................... fairly and adequately protect the purchase rights of the Holders ................ then the Board "MAY" make ............................. such adjustments ..............................
Since Section 4.4 combines both examples 1. and 2. then the word "MAY" is most correct in my opinion.