Are these phrases of praise sound doctrinally and linguistically, or do they have objections against them?

There is nothing to prevent the use of phrases like "O Giver of honor to whoever seeks it from Him," "O He Whose benevolence is ancient," and "O Ancient of Grace."

Explanation of "O Giver of honor to whoever seeks it from Him": - "استكرم الشيء" (istakrama al-shay'): Its meaning is not to ask for His generosity, but rather to ask for Him to be generous or to find Him to be so. - "استكرم" (istakrama) can also mean: He said, "O Generous One."

It is always preferable to praise Allah and supplicate using what has been mentioned in the Quran and Sunnah, or what is similar to it, such as saying "O Lord" instead of "O Master," following the example of the prophets.