The grouting height table occurs in two location in the TMS code. In the TMS 402-16 code it appears as Table 3.2.1 and in the TMS 602-16 specifications it appears as Table 6 (same table in both locations).

The table gives the allowable height than you can drop the grout down the wall based on whether the grout is a fine grout (sand only) or a course grout (contain pea rock) along with the clear dimensions of the net opening down through the wall that will be receiving grout.

The tables allow for grout to be dropped a maximum of 24' for both fine and course grout. Realistically, it is rare that walls are grouted at heights above 12' - 8" because of the need of substantial bracing for an un-grouted wall 24' in height. Also, typically there is a bond beam around the 12' level which makes it a natural location to grout the wall. The 6th Ed FBC, Building HVHZ Section 2122 simply references the TMS 402/602-16 code for grouting requirements and has no other specific requirements other than a maximum age of 1 1/2 hours after the addition of mix water.
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I have included with this post a portion of the Masonry Association's Masonry Certification Workshop slides pertaining to Grouting.

I have included an article below explaining the increased block strength. It includes a copy of Table 2 so that you can reference it as you read this.

The values of f'm are listed in the left most column and are labeled "Net area compressive strength of concrete masonry". Values are given in psi.

The right hand two columns give the required Net area strength of the individual unit to achieve the given f'm. The far right column is to be used if Type "N" mortar is used to lay up the wall and the middle column is used if Type M or S mortar is used in the wall.

Thus,  an individual block with a net area strength of 2000 psi gives you an f'm = 2000 psi.
An individual block with a net area strength of 3250 psi gives you an f'm = 2500 psi.
And an individual block with a net area strength of 3900 psi gives you an f'm = 2750 psi.
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Lets be clear, the project engineering can call for any strength block they desire - as long as it is called out in the project specs that are bid with the job. So if your project specs call for a 2500 psi individual block strength and an f'm of 1500 the 2500 wins and that is what you need to supply to the job.
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On the other hand, if the specs ONLY call out for a masonry unit that meets 2000 psi f'm they MUST accept the current code and accept a 2000 psi individual unit strength. Requiring a higher strength unit than is required by the code, and not called out in the bid documents, would constitute a change to the project.