Cremx,

I think the mill certificate might consists of testing for few A516 material grade.
Please refer to PQR for the Heat/Cast number of the actual material used...
Then look at the "strength" and try to determined from A516 which grade that material should be belong to.

For my opinion, if the A516 plate was Grade 60 or 65 (P.1 Gr.1)... your WPS is valid as per ASME IX.
If the A516 plate was Grade 70 (P.1 Gr.2) during qualification, your WPS is not valid as per ASME IX.
Because your WPS does not cover material P.1 Gr.1, A672 C65/22 as well as S.1 Gr.1 APL 5L X56.

Best Regards,
Noel Tan

For this part, I am making the assumption that your supplementary essential variables are going to apply given the codes you've quoted as your likely on a critical application.
If this assumption is incorrect, scratch it all.

Starting with Joint 1: (warning: Anal retentive content to follow)
From QW QB 422
(Your post has specified that grade 70 is included. Whereas grades 55, 60, and 65 are P1 group 1, grade 70 is P1 group 2 therefore this multicert would require effectively that they are using grade 70, otherwise it would only go through grade 65.)
Sa 516 grade 70   p1 group 2
Sa 672 grade C65 p1 group 1
5L x 70               s1 group 3
5L x 56               s1 group 2

(Per QW 420.1 the S numbers are for B31 series but are effectively the same as the P number listing, also see QW 420.2)
joint 1: B31.3 will kick you back to 2004 Section IX for the PQR.
QW-253 under base metals QW 403.5 is called out as a supplementary essential variable. Going to that paragraph there are a some specified condition test for this variable.
You've stated that the PQR was welded with 5Lx70 and 516 as listed above. Thats p1 group 2 to s1 group 3. The joint in question was welded with 672 to x56 that is p1 group 1 to s1 group 2. Therefore, there is a change in group number in this vs what was welded for the PQR with the P/S number remaining the same same.
Looking at the group # requirements for QW 403.5:

The conditions that are allowed are:
a) same base metal used in production weld. This condition is false
b) a base metal listed in qw 422 same p number group number used in production. This is false
C) does not apply as it's related to nonferrous metals
back in the main body of the paragraph; (this is where you need to be careful)
the first part is false as you only have one set of test, but toward the middle of the para. it states: "if, however, the procedure specification for welding the combination of base metals specifies the same essential variables, including electrode or filler metal, as both specifications for welding each base metal to itself, such that the base metals is the only change, the pqr for welding the combination of base metals is also qualified. In addition, when base metals of two different p/group number combinations are qualified using a single test coupon, that coupon qualifies the welding of those two p/g to themselves as well as to each other. (impact testing was required per your post, the next para. does not apply)

Since the PQR was welded with p1/g2 to p1/g3 and the joint in question was welded with p1/g1 to p1/g2 that change in group number based on the referenced code would make this would appear to be non acceptable per section IX for joint 1. This due to the fact that the Group 1 was not covered in the PQR.

Joint 2 B31.8

821.5
All welding done under this Code shall be performed
under a standard referenced in para. 823.11 or 823.21,
whichever is applicable.
823.21 Welding procedures and welders performing
work under this classification shall be qualified
under the ASME Boiler and Pressure Vessel (BPV) Code,
Section IX, or API 1104.

The weld for this one is s1/g3 to s1/g2 and the pqr is p1/g2 to s1 group 3, therefore by section IX rules it's ok since the s number = p number.
Looking for any variance in API 1104(20th ed)
"5.4.1 General
A welding procedure must be re-established as a new procedure
specification and must be completely requalified when
any of the essential variables listed in 5.4.2 are changed.
Changes other than those given in 5.4.2 may be made in the
procedure without the need for requalification, provided the
procedure specification is revised to show the changes."

5.4.2.2 Base Material
A change in base material constitutes an essential variable.
When welding materials of two separate material groups, the
procedure for the higher strength group shall be used. For the
purposes of this standard, all materials shall be grouped as
follows:
a. Specified minimum yield strength less than or equal to
42,000 psi (290 MPa).
b. Specified minimum yield strength greater than 42,000 psi
(290 MPa) but less than 65,000 psi (448 MPa).
c. For materials with a specified minimum yield strength
greater than or equal to 65,000 psi (448 MPa), each grade
shall receive a separate qualification test.

X 56 min yield is 71 ksi, x70 is 82ksi and 516 grade 70 is 70ksi
under 1104 I could see where this one would be questionable but as each grade above 65 ksi shall have a separate qual test. But since the initial pqr was the equivalent in yield to 516 / x56 to x70, I believe this combination is legitimate  per section IX/B31.8/API 1104 and therefore legitimate. (except for the required qualification of welders)

Summary answer to your question: joint 1 no, joint 2 yes.