QUESTION
Is it possible to update multiple records to Salesforce with Strategy XQuery Transaction 10.x?
ANSWER
Yes. The following Salesforce SOAP API document states update call is used to update one or more existing records, such as accounts or contacts, in organization’s data:
https://developer.salesforce.com/docs/atlas.en-us.api.meta/api/sforce_api_calls_update.htm
So, Strategy transaction document supports updating multiple existing records in Salesforce with XQuery.
STEPS

(: SOAP payload, actual query goes here:)
let $payload2 := ('<update xmlns="urn:enterprise.soap.sforce.com" xmlns:sf="urn:sobject.enterprise.soap.sforce.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
[Begin Transaction]
<records xsi:type="sf:Account">
<sf:Id>[?TF[AccountID@ID]@@1[?</sf:Id>
<sf:Phone>[?TF[Phone@ID]@@2[?</sf:Phone>
</records>
[End Transaction]
</update>')
(: SOAP payload, actual query goes here:)
let $payload2 := ('<update xmlns="urn:enterprise.soap.sforce.com" xmlns:sf="urn:sobject.enterprise.soap.sforce.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<records xsi:type="sf:Account">
<sf:Id>0011N00001CGxVKQA1</sf:Id>
<sf:Phone>1111</sf:Phone>
</records>
<records xsi:type="sf:Account">
<sf:Id>0011N00001CH2X4QAL</sf:Id>
<sf:Phone>12345</sf:Phone>
</records>
</update>')
KB439797 KB439797